NeoSoul
I hope we get an answer on that, I just dropped $$ for the Studio Update because this wasn't made clear until a few minutes ago.  I did not want to loose the polyphonic update as a Editor 2 owner, but needed the "new" tempo mapping.  

If you are planning on doing anything serious with tempo editing I suggest using Melodyne version 4. Please watch some of the video's on their site and read the documentation. There is a ton of stuff they did with tempo editing in V4 which is the sole reason why we implemented this. It was very basic in V2.

I was one of those "V-Vocal works for me" people. Although I had tried Melodyne back in the pre-ARA days and been impressed with it, the lack of integration and having to "read" the file and all that was a deal-breaker.
 
When SONAR implemented ARA, that solved the lack of integration problem but I still wasn't convinced Melodyne Essential was an improvement over V-Vocal. After playing with it for a while I did find the results more natural, and started using Melodyne as appropriate.
 
However, Andrew talked me into upgrading to Melodyne Studio and it's night and day compared to V-Vocal and Melodyne Essential. It's a powerful tool that goes way beyond fixing vocals. Probably the most amazing feat it's done for me was on slide guitar when the last slide up to a chord had the bar at an angle so the high notes ended up being sharp and the lower notes, a little flat. I was sure I was going to have to redo the part but Melodyne not only fixed it, the sliding part itself was unaffected. That totally blew my mind. I've also used it to make sure samples were tuned perfectly and much more.
 
If you can swing the bucks for the upgrade, Melodyne Editor is an incredible piece of software.
 

Noel Borthwick [Cakewalk]

NeoSoul
I hope we get an answer on that, I just dropped $$ for the Studio Update because this wasn't made clear until a few minutes ago.  I did not want to loose the polyphonic update as a Editor 2 owner, but needed the "new" tempo mapping.  

If you are planning on doing anything serious with tempo editing I suggest using Melodyne version 4. Please watch some of the video's on their site and read the documentation. There is a ton of stuff they did with tempo editing in V4 which is the sole reason why we implemented this. It was very basic in V2.

Ok, thank you.
 
I did look at a number of the videos, tried to read the documentation previously.  I still think a lot of the wording is a bit nebulous (understandably to a degree) about the improvements.  Obviously some of the multi-track stuff (studio and the overtone shaping) are clear as real updates.  With the tempo + DNA it is hard to tell how much is improved.  
 
I did not mess around with timing in Editor 2, as I had no idea such mapping was possible.  If this feature works as expected, it is a major update!  Would certainly be cooler if it was 100% integrated within Cake (i.e. didn't rely on having Melodyne installed), but still a much appreciated feature.  

Anderton
 
 However, Andrew talked me into upgrading to Melodyne Studio and it's night and day compared to V-Vocal and Melodyne Essential. It's a powerful tool that goes way beyond fixing vocals. Probably the most amazing feat it's done for me was on slide guitar when the last slide up to a chord had the bar at an angle so the high notes ended up being sharp and the lower notes, a little flat. I was sure I was going to have to redo the part but Melodyne not only fixed it, the sliding part itself was unaffected. That totally blew my mind. I've also used it to make sure samples were tuned perfectly and much more.
 
If you can swing the bucks for the upgrade, Melodyne Editor is an incredible piece of software.
 

While far from perfect, my previous primary reason for paying for Editor 2 was the ability to take audio and convert it to midi (thus transform it into a different instrument with virtual synths).  Just dragging and dropping an audio recording onto a MIDI lane is pretty sweet.  Of course results can be mixed, but with the "right" source is quite helpful for those of us with poor keyboard skills.   

I'm not clear on something.... I have Melodyne Editor 2. Can I install the new Essential 4 AND still keep my Editor 2 or, does Essential 4 wipe out editor 2?

Short answer is yes. Celemony replied to me that upgrading to M4 requires relinquishing the lower version license, regardless of subversion (Essential, Editor, Studio).

For your own peace of mind you may want to email Celemony directly (as this topic is hot all over and may change at some point), but as of now M2 -> M4 is a one way trip.

mettelus
I just confirmed what Andrew said above; and it is, in fact, almost identical to the methodology used by folks when importing tempo maps with M4 just prior to this SONAR release:
 
Example (Say creating a cover):

1. Open the commercial release in Editor 2 Standalone (must be a .wav file). Even Essential 2 should have this ability (?), but Essential 4 is free to those folks anyway.
2. Ctrl-A to highlight all notes (I did this in polyphonic mode, but even melodic should work, depending on the material).
3. Save As... a .mid file. (both notes and tempo map are saved, even in M2).
4. Close M2 Editor, and launch the saved .mid file with SONAR (should be any version of SONAR actually).
5. If X3 or newer, TTS-1 will be inserted, routed, and tempo map inserted (provided no MIDI outputs are visible to SONAR).
6. Create an audio track and import the original wav file.
7. Scoot the audio to line up with the MIDI if necessary (AFAICT scooting MIDI only adjusts the first tempo map value (1:01:000-second value).... BUT copy/paste special will allow the tempo markers to be moved as well if needed).
8. Once aligned, the tempo map matches the audio, same as the original workaround (for M4) prior to this SONAR release.

So, Melodyne (Editor) 2 has always had this "capability," it was just not made obvious with a "tempo extraction" menu option as exists now in M4.
 

Thank you for posting this.  
 
With Studio 4, I followed this method and it worked in X3 Producer.  Very cool.  It is insane we had something like this available (to some degree with 2 apparently) for so long and had no idea it could be done.  
 
I would have tried it with Editor 2, but that was taken away with the upgrade for v4.  So I'm a bit curious how accurate the results would have been without upgrading.  

Just tried it with an acoustic gtr and vocal track combined...with editor2 and it worked fine. Wadda ya know?? Could have used this for sure had I known about it. Toontrack midi played along like a happy camper

OK now the more useful feature for me would be the ability to switch back & forth between the various tracks imported into Melodyne. As it is now, I still have to hunt down the specific region FX and click "open editor" in order for me to adjust it. Any news on if this will be implemented?

Noel Borthwick [Cakewalk]
Some details from Celemony's site.
Melodyne 4’s new tempo algorithms detect tempos, time signatures and any changes in tempo more accurately than ever before. Melodyne 4 tracks precisely the tempo of a live recording, with all its human inconstancy. The ensuing click keeps time with the musicians, not the other way around. And still, you enjoy all the practical benefits of a beat-based grid when working in your DAW.

Hmm, does it really detect time signatures?  If so, are there any plans to incorporate that functionality into SONAR like with the tempo map?  Do the upgrade editions of Melodyne 4 support time signature detection in a way that is easy to get SONAR to pick up (by MIDI file or whatever)?