Not quite, but I think that that’s what Google is moving towards, with it’s new application Google Chrome. Now I’m not normally a techie guy, but I thought the way they introduced the product to the world was pretty cool (see the link above.)
I guarantee you the driving force behind this program is Google’s dissatisfaction with the way current browsers (firefox, ie, etc.) don’t give web apps the same benefits that local apps have. I don’t think it will happen, but Google’s betting that someday iTunes, Word, and maybe even Final Cut Pro will be web apps.