The Vita will have trophies, but the real issue is whether or not they'll be stackable with PS3 games.
It may just be Konami for now (but I think others are considering it) but the idea is to release games on PS3 and Vita so you can play a game on your PS3, transfer your save data to Vita and carry on playing on the Vita while you're out the house. Come back home, transfer the data back to PS3 and continue playing on the console. So the real issue is whether or not the PS3 and Vita version will appear as two different trophy lists, or one.
they get wayyy more sales if it was 2. i know most people in this section will buy the vita for that feature alone