The Adobe Extension Manager is an app that runs side-by-side Adobe CS5/5.5 apps, which lets you manage your Adobe CS extensions. It is installed automatically with Dreamweaver, Flash or Fireworks CS5/5.5, or it can be installed separately using a free download available from Adobe.

If you are running Adobe CS5/5.5 under Lion, you may get an error when attempting to add extensions using the Adobe Extension Manager. Adobe released an update to fix this, available via Adobe’s Update Manager, but many people have reported that it won’t show if you are running Lion… so if you applied this update prior to upgrading to Lion, your Adobe Extension Manager will work as expected, but if you didn’t then you need to manually download the updater from Adobe’s site.
http://www.adobe.com/downloads/updates/