On my 13" MBP I usually get around 5 hours to a charge. My typical usage involves having Mail, Safari, iTunes, Word, and Excel open at the same time on medium brightness, keyboard back light off, and volume on low. I have been through 5 cycles since I got it, and still have 100% battery health. Calibrate your battery using the aforementioned link, and check out
Coconut Battery for some battery stats (if you don't already use it).