This is nice, and should be a feature in the next version of WSUS.
WSUS stores the updates it downloads in directories and filenames that are no where near the original filename. Instead of downloading a hotfix you need many times over for systems outside your WSUS scope, use this little add-on that maps the filenames based off of the information stored in the WSUS SQL backend.
Grab it here:
http://wsus.collewijn.info/main.php?page=hotfixinfo_enu.php