Someone posted this link on the Space.com bbs of an image at the Meridiani site of "white" material right next to the lander that may be like the bedrock material:

http://marsrovers.jpl.nasa.gov/gallery/all/1/p/010/1P129079394EFF0224P2537L2M1.HTML

I noticed the image does appear in the L4, L5, and L6 filter images as well. Perhaps someone could do an RGB "true" color image of this area using the color of the solar panels as calibration?
This is particularly interesting because such white material was found to be widespread at the Pathfinder site. I discuss this in the Habitablezone post below:

Space Sciences
re: Huge Moomaw article on the current views of mars
Posted by Robert Clark on 12/18/2003 5:00:27 PM
In Reply to: Huge Moomaw article on the current views of mars posted by alcaray on
12/18/2003 9:49:09 AM

http://habitablezone.com/space/messages/305743.html

I noticed that neither Spirit or Opportunity has attempted the manouever of spinning one wheel while holding the others fixed to access material several centimeters subsurface. Perhaps it is feared the rovers will get stuck before they even get moving on a trip. However, in the Opportunity image above you can see the white material is quite close to the surface. Then perhaps this material can be accessed by the wheel spinning manouever without any fear of the rover getting stuck.
It is notable as well that at the Pathfinder site, because the material was both white and hard, as evidenced by the Sojourner rover's wheels inability to scratch it, it was concluded that it was either carbonate, such as caliche, or an indurated sulfate, such as gypsum. Since the Opportunity rover is much heavier than the Sojourner rover, it may be able to scratch the material in this case. Also since caliche is harder than gypsum it may be possible to determine which of these is more likely to be the material by how hard it is to scratch it.

Bob Clark