MozillaLinks has posted an article exploring some of the potential features for Firefox 3.6 (code named Namoroka).
Included in the list are performance enhancements, support for Windows 7 jump lists, better theme and add-on management plus a long list of other items.
The article suggests that Mozilla is working around a 10 month cycle at the moment, so we can expect to see Firefox 3.6 possibly in May 2010.