when i was running mightymikes roms my phone would last over 16 hours. 12 of them hours were in my pocket or lightly used on my breaks.
i did however have my phone last 48ish hours.....:
took phone off charger at
4am thursday
went to work and used it probably lightly
after work i went out for drinks and was using it quite a bit, txting and msn messenger
i passed out on the couch and didnt plug it in
woke up at like 10ish friday with the phone beeping and got up and drove to my house.
on the way home i charged it for about 30 mins. it was at like 10% or less when i plugged it in
friend called me and asked to go out again
i went out and phone was beeping though the night and i probably used it lighter then the night before.
got home at 4am saturday and plugged in phone and went to bed.
edit: i would like to add that i have push mail enabled and weather auto update ever 1 hour
but i think on the last night (late friday early sat) i turned push mail off.
on the latest rom im using now i havent been out of the house long enough to see how well this rom is effected by battery. but eventually i will