The Adobe Flash 9 team has released a beta of the Flash plug-in for Linux!
Read the announcement on the Penguin.SWF blog or the release notes, or download it from here.
(Make sure what you’re downloading is the beta update – if you go off on the path to download released versions you’ll end up with Flash 7).
I’ve only tried it on a few sites I know require Flash 9, but so far it is functioning perfectly for me in Ubuntu Dapper with Firefox 1.5
