TTSNotifier is tool I just noticed over on XDA written by Zillode, TTSNotifier provides Speech notification on your Android for Incoming calls, SMS and more.
I haven’t tried the tool myself but I will soon and will be sure to let you know how it goes.
Find out more information on this XDA thread or download it directly @ http://wilma.vub.ac.be/~lhoste/TTSNotifier.php