Just got my phone about a week ago (!!) and I think im averaging between 9-11 hours with heavy usage. Very little actual talk time on the phone, but spending loads of time customizing/acquiring new apps, internet browsing (I've been experimenting between Dolphin and stock browser a lot...multi-touch is nice but the stock browser aligns everything up so nicely and is more intuitive so far), constant gtalk, youtube, pandora, and of course at least an hour playing robo defense. Thats with medium brightness, wi-fi and GPS off.
Turning off Sync and using low brightness definitely extends the battery life by a couple hours. And btw, the Battery Left app is pretty sweet for those of you still shopping around for battery apps...takes a while to calibrate but it gives you numbers for your perecentage of battery life remaining, an actual measurement in HOURS of battery time remaining, and the amount of time an average full charge is estimated to last.