Reader Chris W. writes: After seeing some people asking about it, I just randomly plugged my iPod Mini into the Airport Express to see what happens (the USB port of course). Surprisingly enough, the Express CHARGES the iPod. So to answer that question, you CAN charge your iPod using the Airport Express (which negates my need to tote the power charger for it now when I go traveling.)
Now if Apple could only have a way to pass through the Audio to the Express from the iPod when it's plugged in, that would be a killer little firmware update.... Indeed, you can charge iPod mini and the new Click Wheel iPods from the USB port on AirPort Express (AX.) However, these iPods, at least with current firmware versions, will go into Disk Mode when connected to a data capable port (USB or FireWire) and cannot be forced back into Audio Mode, so you can't listen to your music while charging (as you could with the AC adapter.)
There is still much we don't know about AX, but it's unlikely that it will ever be able to access a connected iPod.