First, don't fret about uploading your module. It works and is compact. The code is easy to read. Rest assured that CPAN has modules of less quality and utility. The name is fine, simple and direct. If others want to improve it, they can send code. If you could describe it in more detail, you might try Apache2::Thumbnail::Descriptor.

That said, I have some thoughts. I would go ahead and use a PerlSetVar to control the cache location. People are particular about where apache can write.

I see why you want to trap the thumbnail size in the location match, but it feels a bit odd. The other module you refer to uses a location for which all images will be scaled to the same size. Different sizes would just need different location matches. As long as their aren't more than a couple of thumbnail sizes that seems like a small burden to me. A set var in each one controls the size. That seems less magical to me, and therefore more appealing. So you could say http://example.com/images/thumbs/100/original.jpg. Everything before the file name would be matched and the file is the name of the jpg which you look for in the original image path.

Those are just my first impressions. Don't let them disuade you from uploading it so others can try it.

Phil