Firefox 0.9.1 and Thunderbird 0.7.1 have been released! Both releases contain bugfixes for some of the biggest bugs in their 0.9 and 0.7 releases. You really should check them out.
Unfortunately, the fix for what I think is a conversion blocker (bug 246078) didn’t make it into 0.9.1. I’m confident it’ll get fixed by Firefox 1.0 Beta, though.