Old Spock is walking off into the night. History has not gone quite as he remembered it, and he has resigned himself to remaining in the past, attempting to ensure that the universe still unfolds as it should. He stops and looks off into the sky, when a figure comes up behind him.
Old Kirk: Hello, Spock.
Spock turns around, reacting in abject shock (both eyebrows go up)
Old Spock: Jim?
Old Kirk: Don't freak out, it really is me.
Old Spcok: (almost inaudible) Fascinating...
Old Kirk: It's going to be okay. I've come from the 24th century. I know how things turn out. And we can leave those kids to live their own lives.
Kirk and Spock then beam away.
After the credits, there's a scene where Kirk tells Spock that they're on the Enterprise-E a Monarch-class starship that's going to be their ride back to the future. They arrive at the bridge, and meet the captain, the newly married Kathryn Sisko, who jokes that this milk-run to the past is easier than when she went back in time to trick the borg into killing the Founders before the Dominion was created.
Spock: Jim, this isn't exactly how it was when I left.
Kirk: Eh, close enough.
Fade to black.