I have used this feature with some luck in the past, but am seeing a strange issue.

I had to use a strange way to show the address example so the forum did not think I was trying to put hyperlinks in.

Setup:
Default Site, 1 app, 2k8 x64

Settings:
Redirect to: /app
checked: only redirect this dir, no subs.

Now if anyone goes to the site like this, all is fine:
httpscolonSLASHSLASHwwwDOTsite.com


It redirects to:
httpscolonSLASHSLASHwwwDOTsite.com/app/

If someone goes to that site, it works. If they go there without the trailing slash though, it still tries to redirect.
Good: httpscolonSLASHSLASHwwwDOTsite.com/app/
Bad: httpscolonSLASHSLASHwwwDOTsite.com/app

The bad (with no / at end) goes to:

httpscolonSLASHSLASHwwwDOTsite.com/app/app/

Any ideas why it would be doing this?