Just to add to the replies you've got already, here's a forum post, someone's created an rpm for it. http://forums.fedoraforum.org/showthread.php?t=205642
Easy to install and update (i.e. you won't have to untar a file and move it to /usr/lib64/mozilla/plugins, not that that's hard).
Henry Wyatt wrote:
Is there a flash player plugin for firefox x86_64 running on fc12
-- Henry E. Wyatt, Jr.