According to MacFixIt.com, Apple made one big preventable blunder in the Mac OS X 10.6.4 update. They included the previous, exploited in-the-wild, version of the Adobe Flash plug-in, version 10.0.45.2. My guess is that this is the version they've been using in the beta of 10.6.4 and they neglected to swap in last week's security patched version 10.1.53.64. That's a very naughty oversight by Apple!
Therefore, if you have not done so already, go grab the very latest installer for the Adobe Flash Player, v10.1.53.64, and install it. Apple didn't give it to you! You can grab it HERE.
Thankfully, Apple's 10.6.4 update installer is smart enough not to remove the updated version of the Flash Player plug-in. Mine stayed intact.
Dear Apple. Considering the well deserved abuse Adobe have had to endure for their blundering crap programming, it would be advisable to avoid blunders of your own and keep up with Adobe's updates! Until this Flash plug-in version oversight happened, Adobe had no legitimate reason to criticize Apple. Now it looks like you're ignoring Adobe's meagre efforts to put things right again. That's not good. You've also needlessly endangered the security of your customers!
Meanwhile, keep an eye out for the Acrobat and Adobe Reader security patch updates that should be showing up any week now...