This may be old news, but I haven't seen it anywhere else yet ... Vasantha C. sends along word that the On2 and ZyGoVideo QuickTime codecs are now available.
To get them, open the QuickTime pane in System Preferences, select the 'Update' tab and then select Install new 3rd-party QuickTime software. Then click 'Update Now...' and wait for it to tell you your software needs updating. Then click 'Custom' and select the new components you want to install.
Oddly enough, QuickTime told me that my software was current, but I went ahead and hit the Custom button anyway. I was somewhat surprised when not only the two codecs were listed, but a QuickTime Update as well. I installed all three without any problems.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20011117002229954