[neilk]

No, the primary reason for these apps isn't advertising. I don't know if they have finally given up or what, but people reading email or composing documents just aren't that distractible.

Google likes the idea of putting your documents on the web because (a) it's a potential business, especially at the enterprise level; (b) they want more structured data on the web to mine; (c) they want a better way to profile you.

Android I don't know enough about, but it's more like an attempt to make phones work more like the PC -- an open-ish standard, rather than specialized, incompatible devices under the control of carriers. I assume Google feels they will do much better in that kind of market.

[djehuty]

There's no doubt you're right about the profiling. I don't know how much they generate from the ads but they're context sensitive. Is it better or worse than ads next to a search? It would be interesting to know.