Its been a couple of times I sleep my computer and when I'm back I get a saving error.
Also, as a docs and iWork user I must admit I'm getting kind of used to autosave. I think it'd be a good (and huge, I bet, in terms of programming, storage, etc) addition. The "complementary" tools that usually come with autosave would be pretty good too (version control being the biggest).
I think it's a great goal though to strive to later in the future.
There’s now an auto-save toggle in the editor sidebar!
Andy Fitzsimon commented
Hey Owen is the toggle still there I've had a bunch of mentions that it's gone. Some people don't want auto save
Kevin Chavez commented
Great! Thanks :)
Zach Lym commented
I will let Aza say my piece for me.
And some technical hints: http://www.azarask.in/blog/post/undo-made-easy-with-ajax-part-1/