I'm in the same situation! I really don't know if I should buy or not!!!
I'm pretty sure the next one would be a major update and possibly even in a different shape (16:9, 16") seeing that Apple's migrating to this aspect ratio.
And you know this current one is not "fresh" anymore and its specs doesn't look good for its pricing now, i.e. not really worth the money.
In the other hand I really want to upgrade my ageing plastic white macbook. I will be doing quite a bit of Python and Matlab this semester at uni and would have to do them in class so I'd like to do it on a new computer with a big screen.