Strange, I don't remember what the main purpose of this patch was either. All I knew was that it fixed several problems:
* When selecting multiple files them in the library and attempting to move them, LimeWire would now actually move the files that were previously selected and not some random files from the source folder.
* You could rename and move files without having to endure the GUI freezes while LimeWire recalculates the hash, - in fact the hash wouldn't have to be recalculated at all.
* you wouldn't loose meta data when moving / renaming files from the library
* you could share / unshare folders more quickly
* metadata and urns would be saved to the same file (sharedfiles.dat) and LimeWire would create a backup copy since it might be corrupted
* when refreshing your library, LimeWire would add files with known urns first and then start calculating hashes of files with unknown urns
* it prevented LimeWire from sending 404s when the Library was being refreshed
* LimeWire would remember alt locs when refreshing the library
* I think it also ordered the folder list alphanumerically and made alternate locations persistant (very useful especially with the improved download mesh that doesn't make it necessary to expire alt-locs anymore)

Some improvements have already been implemented, e.g. the fixes for the upload code that would make LimeWire sending a 404 instead of a 503 reply when receiving an urn request for files that were not available.