The closing narration was done not only by Meredith, but by every regular character. This has been done before in the second season finale.
Thus far, this is the only episode to date where every last cast member (aside from T. R. Knight due to the death of his character) was part of the voiceover narrative. T. R. Knight's character George O'Malley did however get the chance to do a solo narrative during the aftermath of his embarrassing sexual encounter with Meredith.
In the scene when Callie Torres is talking to Mark Sloan while he's showering, Mark is wearing, what's looks to be, a very expensive, waterproof watch in the shower.