"The logic of all this is that by getting people to buy into the "use .NET to build Web services" sell they will be able to convert those people into the "use .NET to build everything" sell, which is ultimately where they want to be."
IBM didn’t make it with SAA (hence their vested interest in Java, and throw some Linux across all hardware ranges for good measure), but Microsoft has been planning for years to come with the universal framework that would embrace everything from PCs and PDAs to minis and mainframes. It’s always handy to have a Bill Gates speech from ’97.
And here’s a bunch of links on software architecture if you have a few hours to spare.