On the Janurary 15, 2011 edition of Adafruit’s “Ask An Engineer” live video chat, I heard LadyAda mention something about “Arduino Amnesia.” After investing the situation a little further, it turns out there are some Issues with the new Arduino UNO Smd edition.
A bug in the new bootloader can be triggered on power-cycle causing the SMD version of the board to not load the previously stored sketch. The good news is there is already a fix for the bug. Either return the board to your Official Distributor or use a ISP to program the new bootloader.
Issues (if I could even use that word) like this makes Open Source Hardware fun!