The TTS app has been in the market since 1.1 and i don't think it is dependent on 1.6. Try going to the market and looking under applications>Software Libraries the exact name is Text-To-Speech Extender
Nope, no app like that in my market. I browsed, searched, etc and nothing. Do you actually have the US Hero?
Just tried my friend's Hero with the same outcome. I'll go ahead and try to load it from the google code site. Thanks for the suggestion.
I submitted a ticket to them in the meantime.
I just tried installing tts_1.5_market.apk from the Downloads there and it didn't work: "TTS Service Extender could not be installed on this phone".
Then i have a feeling it is not signed to work on the Sprint Hero, since it has been out less then a week i think there will be a few apps that don't quite work because they are not signed right. Or sprint doesn't want that app in there it is hard to tell, but i would imagine there will be a fix shortly.