Personally I don't use PLA, but this was just too weird not to share. According to the Makerbot Google Group if you put a little drop of canola oil on the tip of your PLA before you load it you have less problems printing. If you don't remember PLA can be (and often is) made with corn starch.
I think PLA has taken 3D printing down a strange road. Next someone will discover that cedar planks are the best printing surface and you can cure PLA by popping it in the oven at 350 degrees for 10 minutes.