I guess this has been around for some time, however I was not aware of it. I bumped into it in a thread on UbuntuForums, and decided to give it a try.
From the add-on page description, Flash-Aid is a Firefox 4 and 3.5 (and maybe 5 Beta too) add-on which was built to “Remove conflicting flash plugins from Ubuntu/Debian Linux systems, install the appropriate version according to system architecture and apply some tweaks to improve performance and fix common issues.”
Well, I must say it sounds promising at least, especially since the page says it’s designed especially for Ubuntu. Let’s see how it works with Firefox 4.