I played around with SlideShare and uploaded an old PP I had created. This site is fairly easy to use. I did have problems with the SlideCast to include music. I think it would have worked if I had waited long enough. Students would be able to collaborate on PP projects from home especially if they didn't have PowerPoint loaded on their computer. I think Google Docs does the same. I believe it would be a matter of which site was the easiest to use.
(I found out that when I posted the PP to Blogger and tried to edit, the PP changed completely to another presentation that was not mine.)