I'm trying to install Zen Photo here:

http://photos.janicek.com

No thumbnails. Any ideas?

cache and album folders are both 777

It works fine here in a sub directory:

http://www.janicek.com/photography

Anybody have a clue as to why the thumbnails aren't being created on the subdomain installation (photos.janicek.com)?

Take a look at the output from the subdomain image:
http://photos.janicek.com/Cabo+San+Lucas+2005/image/thumb/IMG_3680.JPG

From that it looks like your server path is actually:

/home/.gabbie/jjanicek/photos.janicek.com

Not sure why that .gabbie is there, but that's where the script is located. I'm going to try to do away with the path guessing and just detect them for the next release.

Well, pickle me tink. That did it. I wonder why? My other Zen Photo installation is on the same server but doesn't require the ".gabbie"

That's odd. Oh well, it works. Thanks for your help.