Only if you have money to burn. You wont notice the bump in processor. You might not notice the extra GB of RAM and hard drive speed depending on usage. The only compelling thing that would make me upgrade would be the extra resolution on the screen, and only then if it was causing me a serious problem.
To be quite honest, I'd still be hard pushed saying an upgrade in January would be worth it unless Apple pull something really special out of the bag.
I'm considering replacing my MacBook (which I've had 12 months) with a MBP but theres no way I'll be doing it soon because spec-wise I cant justify spending the money for what I think is a slight improvement.