Jobs has been using it since his NeXT days, probably from the NeXTstep .app extension.



For those that haven't seen this video before, it's worth a watch if your interested in computer history. The work NeXT had done was really a precursor to a lot of modern concepts we use daily in an office. NeXTstep even had Microsoft running scared for a bit, and that resulted in Cairo. (Very anti MS slanted article, but it covers most of the history decently)

This particular video demos NeXTstep 3, released in 1992. An era when Windows 3.1 was just starting to get some networking and collaboration support via Workgroups, and years before Exchange appeared. OS/2 was advancing, but Microsoft was already 3 years divorced from the IBM partnership. NT was still in development, and Novell Netware was the common server for IBM compatible PCs.