Apple's marquee presentation tool may make it easy to look professional when it comes to showing off in front of an in-person audience, but when it comes to sharing those killer decks online the choices have been limited; Keynote's package-based file format made uploading and decoding pretty challenging for most. Among these, Slideshare stood out by allowing Keynote uploads -- assuming you compressed your file to a .zip before shipping it along.
Now that Keynote '09 does automatic compression of .key files (which makes it a lot easier to throw them on a flash drive, among other things), Slideshare has announced direct support for Keynote files. Upload your presentations with glee, and share them at will! The conversion process is still a bit rough around the edges, so in some cases you may have better results by saving the Keynote file to PPT instead... but it's still a welcome development.