Sounds neat! However, much of that stuff is done by Google Voice as well, and you don't get much more integration with GMail, as it uses the same contact list.

I think your service sounds pretty good if you don't have an Android phone, but if you do I MUCH prefer to use the Google Voice application so that I don't get MP3s emailed to me. Instead it streams the messages to you (and naturally the downside is that you have to have a data connection). When I open the message in the app, it shows the transcript and a play button. As I play the message, it highlights the translated words! If I want to hear from a particular section of the message, I can just press the word I want to start from. It's pretty neat!

Also, have I mentioned how GV integrates with GMail? I can set up GV to email me when I receive a voicemail, and it will send the transcript along with the play button right in the email. This is nice if I'm at the computer, so I can click the play button and when it's done it will mark the message as read in GV.

Then there's the other little features I like, such as the ability to block callers by number, personalized voicemail greetings, and more.