I have been using a Radtech BT600 (http://www.radtech.us/Products/BT600.aspx) for a couple of weeks now and I am very impressed, it nicely addresses your USB charging issue and, in a pinch you can use it as a USB mouse also.

The build quality is very good, a solid mouse though it is a little on the small side it doesn't weigh very much and even though I have a lot of bluetooth devices it can pair with it consistently chooses the right one.

Installation was perhaps the smoothest I have ever experienced (Vista x64) - I paired it with the computer and everything just started working within 5 seconds.

It has a convenient recessed off switch on the top, time between on/off switching is about 1 second. Tracking is on par with my favorite wired Intellimouse. The buttons are nice, not too sensitive the left/right are a bit loud, the side buttons are a bit stiff but not bad and the wheel is quiet with a good feel.

I don't know much about the battery life but one review claimed 2 weeks with it switched on all the time.

All in all I am very happy with this mouse.

What about a vibrator?

This is the mechanism used to clean the CCD in many high-end digital cameras and since the rovers are obviously built to withstand very high magnitude vibrations why not use a similar system on them?

The rover could be parked on an incline, identical to the technique used to get them maximum solar exposure during "winter", and then vibrate the dust off the panels.

Even the smallest cell phone has a vibrator, they are small and light-weight I'm not sure how energy-efficient they are but I'd wager the power generating improvement would more than offset the expenditure.