You can charge the PRS from any USB power plug, you just need a cable that plugs into the power port of the PRS and not into the mini USB port.
I bought a fitting plug from Radio Shack and attached it to a spare USB cord. That way I can use ANY USB connector from a laptop, wall charger or what not. This also eliminates the start-up procedure after unplugging from the computer. Wal-Mart has a very small wall charger with two USB outlets, works like a charm...
