Most of the time: Boardwalktech: how to collaborate on Excel

Hmm -- sounds sort of like the (patented) 1-2-3 Version Manager service.

Boardwalktech is tackling the “collaborative” spreadsheet problem where multiple people need to work on the same set of Excel data at the same time while continuing to work in isolation on their desktops. Using a combination of a plug-in for Excel and a patent-pending “tabular” database built on top of SQL Server called the Boardwalk Enterprise Spreadsheet (BES), users can easily specify a range (or multiple ranges) of data that gets dynamically linked between Excel and the database.

Source: Most of the time: Boardwalktech: how to collaborate on Excel