As you all probably know, Firefox 4 is coming, and we all need to prepare for it. Please read my blog post about Firefox 4 Add-on Compatibility: Time to Get Started. If there's anything in your add-on that isn't working on Firefox 4 anymore and isn't mentioned in the documents, please let us know in this forum, or in a comment in the blog post. We want the documentation to cover everything that Firefox 4 breaks.
Like I said in the blog post, the first betas of Firefox 4 are not stable enough for you to produce a final Firefox 4 version of your add-ons, but there are enough changes to be made that it's really worthwhile spending some time adapting your add-on and getting closer to Firefox 4 support.