off the top of my head:

thesps who finished:
Sanaa Lathan
Claire Danes
Maggie Gyllenhaal
Brian White
Hill Harper
Jordana Brewster
Matthew Fox
Natalie Portman
Jodie Foster

those who didn't:
Jake Gyllenhaal
Elisabeth Shue (came back and finished)
Joy Bryant
Matt Damon

In the case of Emma Watson, she's actually quite intelligent apparently and had her choice of Cambridge (a school where many thespians go and acually finish..most of them do) or Ivy League, and settled on columubia.

if im not mistaken, she'll be attending once she finishes the final harry potter 2 part movie....i think they finish this august...