I have successfully upgraded the RAM in my 2009 Mac Mini from 2GB to 4GB. While this may not seem like much of a feat, it requires opening the case with a putty knife, removing antennas and the entire drive assembly to access the RAM slots. I like a lot of things about Mac, but the way they designed the RAM access for this particular machine is decidedly idiotic. But I managed to open the case, install the RAM, and more importantly, put the damned thing back together correctly.