THEORETICALLY, you could using SVG using "animatetransform". If you put the image in a SVG element, you could then apply a transformation to rotate the image to any angle. Problem is Firefox's SVG implementation is buggy/incomplete with no scripting, and Adobe pulled it's add-on plugin for IE. Though Opera and Safari's SVG 1.1 tiny implementation is quite impressive... and they claim Firefox 3 will catch up in that department. (and finally introduce AA) While that's not using CSS, it is the only way I can think of to do rotations client side which I'm assuming is your intent. (either that or you are doing the four-corners two-file trick, and looking to reduce the number of 'panes' even more)
You can use javascript to do this http://hscripts.com/scripts/JavaScript/slide-show-software.php The above script is a free slide show software...