Kev999
It's not just about tuning up a guitar before a take. You might need to verify that something already recorded is on pitch. Softsynths that use samples are not always on pitch. Or sometimes you might even want some notes to be sharp or flat by a fixed amount and need to check it.  An onboard tuner is a handy tool.

All versions of TH2 have a tuner. It's not as sophisticated as Peterson's, but don't forget that Peterson's deluxe version costs $100 and the basic one costs $50. Not sure people would want to see that get built into SONAR's price, especially for Artist (whose TH2 version has a tuner).

Anderton

Kev999
It's not just about tuning up a guitar before a take. You might need to verify that something already recorded is on pitch. Softsynths that use samples are not always on pitch. Or sometimes you might even want some notes to be sharp or flat by a fixed amount and need to check it.  An onboard tuner is a handy tool.

 
All versions of TH2 have a tuner. It's not as sophisticated as Peterson's, but don't forget that Peterson's deluxe version costs $100 and the basic one costs $50. Not sure people would want to see that get built into SONAR's price, especially for Artist (whose TH2 version has a tuner).

 
I would just like a tuner that is separate from an ampsim. Otherwise I generally use the one in Amplitube 3 or GearBox.

It wasn't me who was advocating the Peterson (I've never seen it).

The best tuner for me is MeldaProduction's MTuner that has a ridiculously simple look (I don't need a complicated one ). And I have a dedicated Tuner track (with MTuner inserted) whose Input Echo and Mute buttons are always on. In addition, my screenset for recording guitar has the MTuner window in the lower-right corner of the screen and I can simply show/hide it by hitting just Num 0 (which is the closest key to my right hand's middle finger) to which I assigned the "X-Ray All FX/synths" command. This works perfectly for me. So, no vote from me. 

I always keep a one empty track with Amplitube 3 just for the tuner, even though prefer sounds of TH2. Checking the tuning of the recorded track would be awesome.

yes please! I don't care about the Peterson thing, but sometimes, as a songwriter, you need to get to the point where you record the idea with as little extra clicks as possible.
Ideal workflow is made of a hundred little things like that.

I don't understand, I have a Boss tuner in my pedal booard that is always in line. It is one of the fastest most accurate tuners out there. I guess if you don't play live you might not own one but seems to me 90% of us use this same tuner live. 
My Bass pre amp has a tuner built in but I use a Snark. 
I have Snarks on 3 acoustic instruments. 
Snarks and most headstock tuners are under $20. They are super fast. 
To me pushing buttons in my DAW would be slower than using a real tuner. 
 
I can see the usefulness for checking the pitch of already recorded tracks, but that called Melodyne or V Vocal. 

I think its a great idea.
But why not take it a step further. If it's a pro channel plugin, then why not add a noise generator as well. That helps with monitor setups. If it also had a ping generator, you could use it to better position acoustic tiles. Just saying, the Platinum level is meant to be for producing, why not add some studio setup aids.
 
The tuner would be an artist integrated utility, and the generators would be professional and platinum integrated utility.

This is a great idea,I love sonar,honestly it is the best DAW in my opinion and i have almost every single other one,but it is missing some key elements that seem like no brainers;a good tuner,a qwwert keyboard(i know they are working on it)there are a few other ideas but I am blanking right now,still waking up :)

Until this happens, GTune is ok.
http://www.gvst.co.uk/gtune.htm
Comes as 32 bit and 64 bit VST plugin.

Thought that this video popping up in my youtube feed this morning was funny...
http://youtu.be/tILlZRLhBJE?t=9m52s