Ausiello On Episode 4.11
Question: I'm over the Der-Mer drama. Got any Grey's Anatomy scoop not related to those two sad sacks? - Gina
Ausiello: That final pre-strike episode of Grey's will part with tradition in a major way: Someone other than Meredith will be doing the narration. And his/her name is… *a*l**. Also, there's a reason for the VO switcheroo - and it's a tragic one.
I'm just gonna go out on a limb and say if that little nugget of info is true, then Callie will be doing the voice over. Hopefully, that doesn't mean that Mer is going to die again, or they decide to kill off Callie's dad, or anything having to do with George.