So what are my plugs telling me is wrong?

I meant to post this last week, but I just haven't had the chance.
When I changed my plugs, I was a little surprised to find the old ones looking like this:









Sorry for the crummy pictures, my camera refused to focus on them close up.
Anyway, if you can't tell, they look really blackened around the outside, and then white on the prong that the electrode arcs over to. The blackness would suggest to me that I'm running rich, while the white prongs have me thinking either that I have coolant in my combustion chambers or that I am running really hot (i.e. lean).
Clearly I don't really know what's going on, so maybe some of you could help me troubleshoot?

thanks,
-Jordan