I have been using the Dragon Dictation app on my phone to compose emails and documents.  Works quite well if I let it process the dictation in short phrases.  My iPhone bluetooth function lets me use my speakerphone in my car to dicate, too.  Fabulous! Only problem, my Outlook contacts are not syncing with my iPhone right now (don't even ask why!!!).  So I have to manually type in contact information to send the email (when off the speakphone and not driving) until one by one I get my contacts into my Mobileme account.   The use of the speakerphone to dictate is wonderful.