(Only two years late...I'm sure this is still an interesting conversation to someone...)
While our team is transitioning to FogBugz, lots of folks are still more comfortable "living in" email than in FB. We've written a little program to parse instructions out of mail sent to a special mailbox. The program then calls the api to update bugz. Right now, we mostly use it for user assignment (TAKE Case 1234 assigns the case to the sender), but we're growing it as needed.
For folks who want tighter email integration, that may be the way to go.