This is very a debatable question, see this link on the same question for the i7 iMac. http://www.ifixit.com/Answers/View/2029/...
We haven't had upgradeable processors since the G4 towers, but it appears Apple has gone back to socketed processors. I haven't worked on a i7 MacBook yet so I just don't know, but when faster processors become available I'm sure the folks on iFixit will be some of the first to get info on it, so keep posted. Here's an article that gives me a great deal of hope for upgrading machines in the future: http://www.hardmac.com/articles/335/page...