Autosave has been part of Excel for ages. I had it enabled back in the early 1990s with the version that was distributed alongside Word 6 as part of Office 4.3 (I don't remember the Excel version number).
Current Excel Autosave when used with ODSP is different -- changes are individually autosaved (change cell, autosave, format table, autosave). They're completely transparent to the end user.
