Generally, seats in front of an exit row or emergency exit row do not recline. The airlines want to make sure the aisle is not blocked by a reclined seat if there is an emergency. That is why there is no recline or limited recline on many of the overwing rows (location of emergency exits).
On their new A319s and A320, however, US Airways has a locking system that locks the seats while on the ground, during take-off and during landing, but allows them to recline while flying at altitude. At this point, I am not sure how widespread this feature is.