Take it with a grain of salt, but here's a link to some supposed shots of next year's release of OS X Leopard.
Note a new version of Internet Explorer being used natively in OS X. Also, a tabbed Finder window (brilliant) and a new Address Book/Calendar icon in the Dock. The second image is apparently a screenshot of a desktop Fast User Switching transition. It would be interesting to see this in motion.
IF these are even real.
P.S. Somehow, I doubt I'll ever switch back to IE, even if they do give OS X users the same version as Vista users. I've been pleased with Firefox and Safari (although I now use Firefox almost exclusively) and am sorta-kinda keeping an eye on how Camino turns out. Despite the rave reviews Camino's received, I haven't noticed anything different enough about it to make me want to switch, not to mention there are hardly any extensions and themes available for it.