Is there any way to manually (or automatically) change the type of a file uploaded into the briefcase?

My test environment is a RHEL4 server running v5.0.2 OSS. A colleague uploaded a Visio file to a briefcase and then tried to download it again; he was given a 'save file' dialog for a file ending .VSD. He does have Visio installed, so my thought was that it wasn't giving the right mime type and that his browser might not have sent that in the initial upload.

Also, is there any plans to have any content revision for briefcase files? Sort of a merge of Documents and Briefcase, where the server might keep copies or diffs of changes so you could roll back. I know this could probably be achieved by creating a document and attaching a file to it, I was wondering about a simpler form. It would also be useful if you have the briefcase via webdav. I was browsing through bugzilla but may have overlooked if there was already a RFE, so I thought i'd check.