A 2.0.1 update is now available through the update software feature. This fixes a new incompatibility with the Exploratorium site which suddenly appeared, which was preventing images from being downloaded.
I've updated Google Code with the 2.0.1 packages as well, but I've run out of space there, so only the Windows version and the Mac on Intel versions are posted; Mac on PowerPC is not. I'll have to either get more space there or (more likely) just start putting the files somewhere else. I don't think many people use the Mac on PowerPC version.
I hope we're good to go now, since Oppy is off to see new sites.
One last thing... Midnight Mars Browser 1.x will no longer work to download images from Exploratorium, and I don't have time to fix it. Please update to 2.0.1, or if you simply cannot for some reason, you will have to use the option to download from the JPL site in 1.x.