interesting that it is in browser, but they say are "rolling it out... on Android with Froyo (version 2.2) and on iOS devices (version 3.0+) including the iPad" what features does the android 2.1 browser lack the prevents it from being available there?
For Pete's sake, it's about time. I think that the lack of mobile editing has been the #1 thing that's prevented me from using Docs for any serious work.
I've also used PlainText, which is without question the best text editing tool on the iphone and ipad. The dropbox integration is sick. http://www.hogbaysoftware.com/products/plaintext