Well it looks like we finally got our wish. It appears that a company, Loquendo Technologies has indeed released a better TTS speech engine for the Android. It is available in the Market. It requires Froyo 2.2. Its nothing amazing mind you but it does appear to sound better than the stock voice. There are some samples on their website to get an idea of what it sounds like. I haven't taken the $5.00 plunge yet and bought it for my D2 but I might. We Android owners could finally be on our way to getting some choices for voices. Look out Tom Tom.
Loquendo TTS for Android
Loquendo Technologies for Android