One of Mountain Lion's features is Dictation. Here's a 2 page article:
http://appleinsider.com/articles/12/07/13/inside_os_x_108_mountain_lion_gm_dictation_speech/page/1 that describes Dictation and shows screen shots. It's currently supported on the new iPad and iPhone 4S, also.
If you're using Dictation why not drop us a line so we can pass along your assessment of the experience? You'll see the email directions in the column, About PMUG, on the right side of the homepage.