Is this coming? It seems pointless to be able to merge messaging on iPad on ios6 but not your mac because then your messages will still be split. It isn't available in the GM so I was just wondering if apple had mentioned it at all.
I would expect it to show up when iOS 6 is released this fall. Unifying your number to your Apple ID seems to "require" your iPhone to run iOS 6. Since most people won't be running iOS 6 until this fall when it is released, it wasn't included in 10.8 just yet.