In a somewhat desperate attempt to counter FireFox' rising popularity, Microsoft have made it possible to experience tabbed browsing in Internet Explorer even before they ship version 7.0. To enhance MSIE6 with tabbed browsing, you can download and install Microsoft's MSN Search Toolbar.
But if tabbed browsing is all you're interested in, the toolbar is an annoying host - It adds an MSN Search textbox to your MSIE Toolbars and defaults to installing the MSN Desktop Search (Microsoft's answer to the Google Desktop) on your computer.
The document tabs themselves are a refreshing addition to MSIE, but the implementation is unfriendly and incomplete - Typical signs of the “time to market” stress the developement team must have been under.
I've noticed two annoying things (three if you include the wasteful addition of the MSN Search textbox to my Toolbars):
The tabs are “alive” only when the MSN Search Toolbar is turned on. So, when you switch to Full Screen mode (F11), thereby turning the Toolbar off, and return to normal mode - all the tabs are gone and you're only left with the one window that you were watching. Quite annoying.
If you close the Internet Explorer window, you lose all tabs without any warning. Very unfriendly for people who are just getting accustomed to tabbed browsing. Microsoft should have better learned the lesson from FireFox where you are prompted with a reminder that the action will close all tabs.
All in all, this is a welcome enhancement of MSIE but also an indication of how reckless the Microsoft developement process is. “Time to market” seems to take precedence over Product Quality and Usability.