I use CreativeCommons.org all the time to find legal and free images for my articles, so I was extremely disappointed to find that CC Search was removed from the drop-down search bar in Firefox 4. And it’s also not listed in the Search Tools section as an Add-on.
I thought it was gone, but it turns out that if you go to Creative Commons labs, you can install the CC Search beta interface.
It doesn’t work the same as the old search bar, which previously went to a more user friendly interface (in my opinion), but it’s still handy. You can also revert to the old version by clicking the link in the top right corner of the page that says “Switch to tabbed search interface,” which you can see in the image below.