> Can you imagine using an actual productivity application in the browser?

I'm not sure what type of applications you're referring to, but if you're including word processing in that, then I can't imagine not using either Google Docs, or whatever might one day come along and be a reasonable alternative. If I'm using a word processor, it's because I want someone else to be able to read and, quite often, contribute to what I'm creating. That is far, far less painful using Google Docs than Pages or whatever the alternative might be.