Just wanted to bump in
I experience the very same issues. I have a Galaxy Gio and I hardly do anything, call-wise. My average is 1~2 calls a day. However, I do some tweeting and reading e-mails through the built in Gmail client (Android Gingerbread v2.3.4). I also listen to some music, using the built in player. Sometimes I disable Wi-fi when I go out, sometimes I don't. However, now down to battery, it sucks. Never more than a day. I'm starting to think I have a crappy battery. My wife has a Galaxy Mini (GT-S5770) and it's battery is almost full at the end of the first day of charge. Mine is at ~15% after 10h. Since our phones uses the same batteries, I've thought about switching batteries, just to see if there's any difference.