I have noticed that alot of directory owners have not updated there Thumbshots.org code since they updated it, please everyone check your directories then check with your software developer for the update. I know eSyndicat have updated theirs.
I was investigating thumbshots.org. Is it worth paying monthly to have thumbs of your site? It seems like a useless feature. Is there other free options for this type of service? Also, I'm running, eSyndicat 2.5 and the thumbs don't seem to be working and I don't feel inclined to upgrade to 3.0.
There's a few around, Shrink the web and pagepeeker are another couple. Some people do their own as well...
There are some decent benefits to doing your own or even a hybrid system. If those thumbs can be stored on your own server it reduces the calls out to third party sites when a page loads and speeds up the load time.