Recently for our web site, we ran into a problem where our URL rewrite module wasn't working with non-.NET-handled files. As you may know, IIS7 supports using URL rewriting with all kinds of files without too much web.config editing.

The solution was simple: our host did not set our web site to Integrated Mode in IIS7. Once they did, all of our rules were working.

For more information about IIS7 settings, take a look at this post:

Wildcard script mapping and IIS 7 integrated pipeline