Cheah Chu Yeow has an excellent run-down of the new features in Thunderbird 0.8 (with screenshots), which is apparently due out shortly. These include:
- RSS (and Atom) integration - this hasn't yet been activated in nightly builds, but will work like Forumzilla does now.
- Better blocking of remote images - the behaviour is now more like Outlook Express 6 SP2 where a message is shown if images are blocked. It's also turned on by default.
- Global Inbox - when adding a new POP3 account, you can choose to have mail delivered to Local Folders, as opposed to creating a new set of folders for each account. This was a big gripe among some users with many accounts, and it now means that Thunderbird can more closely imitate OE
- Get All Mail - the Get Messages icon now has a submenu that also lets you get mail from all accounts or select a specific account. This is a feature in Mozilla Mail that was missing in Thunderbird.
- Better quick search - it offers a greater level of control and allows you to use it to search the message body too.
- Ability to import mail and settings from Mozilla Mail
I say this about every release, but Thunderbird 0.8 is going to rock. If you want to try these new features out for yourself, get yourself a nightly and start playing.

I’m specially looking forward to the RSS/Atom integration!