The seventh beta of the upcoming Firefox 4 release was released yesterday (10 November 2010). Clippings, Delicious Post, Panic Button and Send Tab URLs have all been tested against this new beta release, and are now compatible with it. If you upgrade to Firefox 4.0 beta 7, no further action is needed to make these extensions work.
Missing status bar in Firefox 4.0b7
The first thing most users will notice when starting Firefox 4.0 beta 7 for the first time is that the status bar is gone. And as a result, the Clippings status bar icon is missing, and so is the Delicious Post progress icon (that cute little icon with the animation that appears when posting a URL to your Delicious account).
You can make the status bar UI for those extensions reappear by enabling the so-called Add-on Bar. To do so, choose View -> Toolbars -> Add-on Bar in the Firefox browser window. The Clippings icon and the Delicious Post status icon will appear in the same places on the Add-on Bar as they would have in the browser status bar in older versions of Firefox.
Please note that I am NOT responsible for the missing status bar in Firefox. Direct any comments about this Firefox UI change to the appropriate Mozilla forum discussion. See also this Mozilla Support forum post.
Support for Firefox 3.0 discontinued
Firefox 3.0 is no longer supported by Mozilla; therefore, compatibility with this older version of Firefox has been dropped. All AE Creations extensions now require Firefox version 3.5 or newer.