One of the problems Microsoft foresaw was getting new users to join Messenger when so many people already used the other chat programs. The trouble was that the programs, then as now, didn’t talk to one another; AOL didn’t talk to Yahoo, which didn’t talk to ICQ, and none of them, of course, would talk to Messenger. AOL had the largest user base, so we discussed the possibility of adding code to allow Messenger to log in to two servers simultaneously, Microsoft’s and AOL’s, so that you could see your Messenger and AIM buddies on a single list and talk to AIM buddies via Messenger. We called it “interop.”
Came across the behind the scenes story about what went on with the MSN Messenger and AOL when Microsoft was trying to make their messenger client talk with AOL. Bought me back so much memories of the days when MSN Messenger was almost a daily interaction platform. Have a read about the story at nplusmag.com
On a similar note you can also check out on Joel’s Strategy letter on how Microsoft made excel the leading software in spreadsheet applications.