I say potentially because as yet, Google Docs mobile is read-only. Which is a shame, because I want to put it in my sidebar.
I divide my Firefox window into three using the Split extension, creating an artificial two-pane sidebar (the official sidebar can't be split). I keep my Meebo IM list in one pane and my Remember The Milk task list in the other.
Mobile optimised versions of Web sites such as RTM and Google Docs also happen to be the right shape for sidebars. Once the functionality catches up, and you can do everything with the mobile versions you can with their online bigger brothers, then I'll stick them in the sidebar as quick-access versions of the sites that I would otherwise have to keep navigating back to. That would be a big win for me, as Google Docs is far and away the site I use the most, but it won't fit in my sidebar as it inexplicably won't resize and create scroll bars.
Until Google Docs mobile goes fully fledged, I'll settle for a Firefox extension that puts a button in my toolbar for creating a new document without having to navigate to the site. That would make me very happy indeed. Get to it, extension monkeys.