While Adobe doesn't offer a native x86_64 version of Adobe/Macromedia Flash for Linux, Microsoft and Novell will be offering a 64-bit edition of the Silverlight binary codecs for Linux. Miguel de Icaza had posted this information today on his blog.
This might just be a good thing, but being it based on .NET and as such Mono, is the overhead of Mono worth it?
It shouldn't make much difference. The overhead of C# is generally agreed to be around 4% compared to native code, whilst being much easier to work with than ActionScript, and faster too, in a lot of cases. Try it out some benchmarks on http://bubblemark.com/
Adobe better really get their act together by making flash much more open-source-friendly, and they had better do it soon. I normally wouldn't be worried about something like this since it's going to take a long time and lots of luck for something to overtake flash, but if anyone can do it it's Microsoft. Not that I'm a huge fan of Flash or anything, but when you Adobe lock-in to MS lock-in then Adobe starts to seem like a good choice.
And now an x86_64 version of this new player? All this Mono/Novell collaboration with MS is making Adobe (which is now responsible for the ages-old Linux flashplayer in comparison) look pretty bad.