MacSpeech is ditched their own speech recognition engine for the market and technology leader Nuance in 2008. Then, Nuance bought the Macintosh speech recognition program earlier this year, and the "MacSpeech" brand was up in the air. Now it is officially Dragon Dictate 2 for Mac, which uses the same best-in-class speech recognition engine as Dictate 11 for PC. (MacSpeech Scribe still exists)
Another nice thing about this version is that it allows multiple microphone profiles per user.
One other interesting new feature is the "mouse movements" via speech. You can actually move your mouse around the screen with voice commands.
Dragon Dictate 2 for Mac is available for $199 retail package or $179 for software download only and $49 for an upgrade from MacSpeech 1.x.