Now, presumably Microsoft itself will adopt the .NET approach, and we'll see versions of Word, PowerPoint, Excel, etc, with a more uniform feature set and user interface. And today I can explain it in a whole new way. It's a like a bathtub with its plug pulled and connected to a shower head on the floor below, owned by your competitor. To keep the tub full you have to keep adding water, otherwise it will empty out. Maybe I want to go where the water is warmer, or the tub deeper, or whatever.
SOAP opens the underside of application environments, it pulls the lock-in plug.
Think of it as the advancement of the Internet into the architecture of applications, beyond the browser, now it makes no difference if your app is written Java or Perl or runs on Unix or Mac. This was the promise of Java in a way, but the force has been removed. You can use whatever OS you like and not be captured by Sun. Microsoft keeps fighting the Java war, probably mostly for the benefit of the press. The war over Java was over the day IBM made SOAP run in Java.