I would wait for the MkIII and see if I want to upgrade and if I do then you can buy my MkII for a really good price if the MkIII is really as super-fantastic as the rumors/fanboys say.
I think I'm going to start to tell people to wait, otherwise who will buy all the used MkII's?
Actually, in all seriousness, I might be tempted to wait until the end of Feb if it were me.