I stumbled upon this when skimming through the Zend_Cache code. I don't have anything that uses Zend_Cache and I don't have admin rights on my Windows workstation to unset system environment variables so I can't verify this, but I figured I'd bring it to somebody's attention.

In Zend_Cache_Backend::getTmpDir() at Line 178, if Windows is detected and if no temporary directory path is found after exhausting all the environment variables, '\temp' is returned (which would be 'emp'). I believe this should look like the return statement a few lines above on Line 172 ('\temp').

Feel free to mark this as invalid if this isn't really a bug. Most of my expertise here revolves around Zend_Gdata. :)