It's not clear whether this is a full-blown Grey's Anatomy spoiler or only rumor material, but sources, including Michael Ausiello of TV Guide, have hinted that someone who shared big smooch in the finale may be pregnant.
Which Grey's Anatomy character it be, if this were the case? It would have to be Meredith Grey or Callie Torres, we'd think, for obvious reasons.
Considering all the time spent in the on-call room with Mark, Callie would seem to be the most obvious choice - and throwing a surprise pregnancy into the mix with her fledging lesbian romance would certainly create big drama!
On the flip side, might it be possible that Meredith Grey is somehow pregnant with Derek Shepherd's baby? How long have they gone without ... you know? It's unclear, but with production Season Five (!) underway soon, it's fun to discuss.