Adobe released a beta for Flash Player 10 yesterday, and it was available for windows, mac, and Linux all at once.
It doesn’t really fix any of the famous problems in Linux, like transparency or a 64bit version, but the speed increase is dramatic. We’re working on an all-flash toy for HisKids.net and with flash player 9 it took about 4 seconds to load. With 10 it takes about 0.8 seconds.
I haven’t had any problems with it at all, I’ll be running it as my main player until it blows up.