I hope that is a "friendly kiss" not a "romance kiss"...
Is there a picture that shows them kissing? All I'm seeing is one with a hug.
Doesn't matter, though. They've kissed before. And the Doctor is attracted to Clara, as referenced by the end of Nightmare in Silver. And since the Christmas Special is 11's swansong, so what if they do kiss? It's not like they'll push a Clara/12 relationship.