I reckon if you have the money and it's going to be suitable for your needs then go for it.
I had the 2.4GHz model from the late 2008 update (so no built in battery and lower CPU speed, but otherwise pretty similar), and it was a fantastic machine. From what you say you want to use it for it should handle anything you throw at it admirably.
Yes there may be an update next month, however there's no concrete proof that is going to be the case. Everyone was saying it had to be February because of previous release schedules, and yet still no update. The longest stretch before an update was 266 days and it looks like we're about to surpass that mark.
End of the day it's a case of working out which is stronger, your need to have a notebook or wanting to wait to get the latest and greatest, however it's not like you're gonna be disappointed with a 2.66GHz MBP.
Quick question, you mentioned about being at school and having finals, have you looked into the educational discount? Sorry if it's dumb question but haven't been a student in many moons and have no idea how it works lol.