This issue has been resolved. See No More Little Sandwiches. And I'm still a fan of PBWiki.
I just took a look at my blog and wow, all of my images that I've been keeping on PBWiki for use on my personal Wiki and for use on my blog have randomly started having an image overlayed on top of my images with their logo. You can see two examples below that I've saved from PBWiki and then uploaded to blogger.
I don't think I received any kind of warning about this. That's pretty bad. So, I go from being a raving fan telling people about them during presentations (literally yesterday was one example) to a person who now can't recommend them because who knows what they will do in the future.
Now I have to go out and figure out who I'll use instead.