I have an early 2011 (May) 13" MBP with 4GB memory. I haven't cracked it open, but did it come with 2x2GB or 1x4GB sticks? I'm guessing 2x2GB, but I'm not sure.
Well, it seems pretty obvious when you put it that way
I don't know why I didn't think to check that, but yes I do have 2x2GB. I bought 2x4GB for my new Mac Mini at Best Buy this morning and was thinking about doing the same for my MBP.