For SOMEONE that can change things?
I was looking thru the "Playground" and under "Connecting and Powering Arduino" the sections that show the: adapter, 9v and BIG battery, all show the the plug as a 2.5 mm. Shouldn't they say 2.1 mm? I know that I'm using 2.1 mm. Could keep someone from wasting money on parts that don't work, or having problems with their power supply.