I have been using Organizer - a very useful plugin to help upload and organise files on your server.
If uploaded Organizer - Version 1.2.1 to my test blog.

When I activated the plugin - no errors were generated. However, when I tried to update options - I wanted to add SWF as an allowed file type, the update failed (twice)..

I then tried browsing for existing files in the Uploads folder. This function worked - as did a file upload, and a file resize.

So - it seems that apart from being unable to change the list of allowable file types, the plugin can be used on WordPress 2.5.

I will take a look at this minor problem over the next few days and see if I can quickly fix this inability to change file types.