Did a search for "USB Power" and "power things with USB Port" and didn't find anything. So don't yell at me for asking this please (LOL).
I tried it, and I can power both my Boss wireless system and my Shure battery charger through this port. It worked great.
But I also recall somewhere on these forums that is is not recommended and not to do it at all.
I just want to be sure one way or the other, as it would be really nice to be able to just bring one USB-mini cable and keep the wireless charged up directly.