No doubt with huge projects, it only makes sense to have a clear and concise roadmap, and stick to it. Over at the Mozilla Wiki, there is a huge list of some of the features being planned for these future versions.
Nothing catches my eye right off, except for the Download Resuming. It would be nice to not have to resort to using a 3rd party program. It is disheartening to see that many features will not be available for quite some time, but are already being taken care of with small extensions. It’s good to see what’s coming though, so take a gander at the list here.