If you use Firefox on Mac, you should be aware of this matter. In my case I'm on Snow Leopard, but I'm sure the same applies for older versions.
I upgraded to Snow Leopard over the weekend, and the 10.6.1 update duly popped up yesterday. I saw the release notes bullet item:- Includes an update to Adobe Flash Player plug-in version 10.0.32.18
And assumed this would cover me for the recently-discovered Flash vulnerability. This morning the Firefox 3.5.3 update popped up as well, and I applied that. When it restarted it gave a warning that I also needed to update Flash, with a link taking me to the download page for Adobe Flash Player version 10.0.32.18. At first I was about to assume the OS upgrade took care of that, but then I thought "you know, Firefox probably manages its own Flash plug-in". Surely enough, I went to Tools →Add-Ons->Plugins and saw that the plug-in was indeed not up to date.
So I did download and update Flash from the Adobe site, and now it shows the correct plugin:
Please do make sure you're similarly up to date, because the v10.0.22 vulnerability is a nasty bit of work (if you're still on Flash 9 you want to make sure you're up to 9.0.246).