Like Firefox, Mozilla's popular email client Thunderbird is part of a new rapid update cycle and has hit version number 11 six months after the release of Thunderbird 7. Thanks to the short development cycle, there isn't too much in Thunderbird 11, but one change of note is that tabs now lie at the very top of the window, above the menu bar. Mozilla made a similar change to Firefox back in 2010, but unlike the newest version of Thunderbird, Firefox users could move the tabs back to where they wanted.
According to Mozilla software developer Mike Conley, there is a good reason for the change: tabs on top allow the menu options and toolbars to change based on what kind of tab is open (e.g. whether it is an inbox, calendar, IM, or compose tab). While there are few different types of tabs in version 11, Conley says that they'll be introducing some more in the future, and that by mandating that tabs remain on top they'll be better able to improve the user experience. Seems fair enough to us, but we're sure some will resist the change. Other than the new tabs position, the update brings Growl 1.3 compatibility and the usual "various security fixes." Check the source below for the download links, and let us know in the comments how the new tab layout is treating you.