Mozilla has been fostering a very good extended development ecosystem for Firefox, but the problem is that every time Mozilla releases a new version of Firefox, developers have to deal with compatibility issues. The next version of Firefox is 3.1, and Mozilla promises that Firefox 3.1 is compatible with 90% of the most commonly used extensions. Firefox 3.1 is still some way off, but at the moment, only 28% of the most commonly used extensions are ready.