I agree it must be something about the way Facebook runs flash applications. I'm not rooted and have got the 'official' 2.3.
I'm able to go to flash websites fine, BBC iplayer works well, as do sites with flash games. However, when I try playing Bejeweled Blitz or Zoo World on Facebook, it looks like it's loading correctly, and then I quickly see the start screen before the game area turns white with a 'play' icon in the middle of it. Pressing this icon just reloads the game until the white screen re-appears.
Has anyone been able to play Bejeweled Blitz on Facebook on their X10?