Seems Omni Kontakt hybrid-ish.  Its $79 for Platinum, $99 otherwise.
 
 
From youtube description:
 

Introducing Rapture Pro
Rapture Pro is the most advanced synth Cakewalk has ever produced - combining algorithmic and sample-based synthesis in an intuitive design for musicians of any skill level. It delivers the best parts of Dimension Pro and Rapture in one instrument, perfect for your studio or live setup. Rapture Pro includes nearly 1,000 new sounds that span all music genres, and also loads every legacy sound and sample from its predecessors. 

Rapture Pro is designed to adapt to your personal workflow. Composers can easily find and preview commercial-ready sounds by top designers in an intuitive new Browser. Performers can move from studio to stage with Rapture Pro's new instrument page - a dedicated view with fast, efficient controller mapping for real-time expressiveness. And sound designers can create a signature sound with Rapture Pro's Edit mode - which features extensive layering and mixing capabilities that let you stand out from the crowd.

What's New in Rapture Pro

The ultimate fusion - layer synth sounds with real-life instruments
Redesigned UI - Bigger, cleaner, and more organized
Master your sounds with the improved Mixer Page
Dedicated Browser page for finding sounds quickly
Play on-stage or jam in the studio with the new Instrument Page
Assign up to 8 macro knobs and 2 X/Y pads to any parameters in Rapture Pro
Nearly 10 GB of carefully curated sounds from professional sound designers
Vector Mixer for creative, real-time mixing
2-click MIDI mapping for quick, spontaneous controller assignments
Surgically carve out your tone with the redesigned EQ
Take advantage of VST3 technology with Rapture Pro
Load new and legacy expansion packs

 

Product page now up:
 
http://www.cakewalk.com/Products/Rapture

Hopefully it means an end to the silent treatment.

Would someone test it and drive it hard and tell me if you have to close and reopen sonar to recover?

I think this is an addition I'm going to be willing to pay for.

This looks like Dim Pro and Rapture combined using the Z3TA+2 interface.
I will only buy this if they hand out regular services releases (like they didn't with earlier versions).
Having said that $79 so will probably wait for sale..
 

Rapture and Dimension Pro combined but with an adaptive workflow and GUI along with new sounds and features. The GUI has also been redesigned and adapts depending on what you are doing (composition, live performance, sound design).
 
Check out the web pages and sound examples. Very powerful synth and we are excited to finally announce it.
 
 

and what do we do with our existing Rapture and Dim Pro instruments? Is this to replace them? Any discounts for existing owners?

Very interesting. The evolution continues.
I have enjoyed using Rapture and DimPro for several years. Similar, yet different, a melding of the two seems a natural direction.
Will it support previously installed Rapture/DimPro libraries?

BTW I am hoping with this we FINALLY get control of where we put our sample files in a settings section?
This and a stated bugfix policy will definitely make me consider buying it tomorrow (thinking about it)..

joden
and what do we do with our existing Rapture and Dim Pro instruments? Is this to replace them? Any discounts for existing owners?

There's an introductory upgrade offer for $99. If you own SONAR Platinum, it will be $79. You can keep your existing Rapture and Dimension Pro. Expansion Packs you purchased for them will be compatible with Rapture Pro along with the existing factory content that shipped with them.

perfectprint
 
 
Seems Omni Kontakt hybrid-ish. Lets hope it in the next update.  edit: Its $79 for Platinum, $99 otherwise. I think with Omni 2 being released Ill stick with that upgrade. 
 
 

 I like that they are doing this but I'm at the point I don't need another synth in my life.