I found an interesting setup for Thunderbird 7 on the OMG!Ubuntu! blog. I installed the necessary extensions and theme file, but I later disabled Folder Pane View Switcher because I didn’t see a use for it with my setup. The net result came out just like the example and makes Thunderbird work a bit differently.
For example, the only place that I could find to “Reply to all” was inline at the bottom of a message in the view pane. That actually works better with Unity, because having multiple windows of an application open in Unity makes it a pain to switch between them. There are other button differences, with some buttons replaced by embedded hyperlinks. I am still exploring and may have more comments later.
I generally like the threaded conversation view like gmail. Although a bit different than the consistent stock Thunderbird message interface, it’s easy to use and helps tidy up my large collection of emails.