Mozilla Thunderbird 0.9 Released has released Thunderbird 0.9. New features include Saved Search Folders and Message Grouping, in addition to other smaller changes and bug fixes. From the Thunderbird 0.9 release notes:

Here are the highlights for this Thunderbird release:
  • Saved Search Folders

    Saved Search Folders display messages based on previously set search criteria. For example, instead of filtering messages into a new folder, you could create a Saved Search Folder that lists all the messages received from a certain person over the past 30 days, even if those messages are stored in different folders and subfolders.

  • Message Grouping

    You can now group messages in a folder by attributes such as date, sender, priority or a custom label. For instance, a folder grouped by date will group messages from today, yesterday, last week, etc. into self-contained groups in the message list pane. (View > Sort By > Grouped By Sort)

  • Other New Features

    Messages with attachments now get marked as such in the message list pane immediately and not when the message is displayed.

    Improvements to Thunderbirdis Global Inbox support for POP3 users.

    The new quick search bar introduced in 0.8 now features a clear button when search text is present inside the quick search box.

    Fixed a regression introduced in 0.8 where a user could not change the local folder path in the Account Manager.

    Improved offline support including fixes for common offline-related problems.

    Improved privacy controls block remote content in e-mail messages from senders not in your address book.

    Long file attachment names are no longer truncated in the message pane.

    Bug fixes too numerous to mention!

Thunderbird 0.9 is available for Mac OS X, Linux and Windows. Download links are at the Thunderbird home page.