Why try to decipher some sort of logic behind their version numbers? Who knows.
All I can tell you is that the version that supports the new Google Voice service, as of right this minute is:
3.2.2 (Build: 5829EX)
I didn't write down what the beta version was, but I believe it started with 3.2.1.
As of today, I do not know what else, other than the firmware update, may be required, so my disclaimer is: I would not suggest trying to find that version on their firmware server and install it manually, because I don't know what would happen. I'd wait until it is pushed to you, or until Polycom provides some direction. And, I do not believe that in-warranty vs. out-of-warranty status will matter. Given that Google Voice will not work without the new firmware, I believe they will make it available to everyone.