So... Apple anounced yesterday the availability of Safari 3 (beta) for Windows. Why?
Step back for a moment. We are in the begining of a "browser is the platform" war. Adobe has Apollo. Microsoft is pushing Silverlight. Mozilla has not been strong on this, but XUL is a great platform to develop applications on (see Songbird and, correct me if I'm wrong, Joost).
An now Apple with Safari. You may think that Safari is "just a browser", but I have the impression that Safari will soon be able to control the environment outside the browser. Did you see that "web2.0 addressbook-in-safari demo"? In iPhone, you can call the number you see in the browser just by clicking on it...
IF iPhone does well, then Safari 3 will be a desirable platform to develop upon. Being able to use Safari as a cross-platform (OS X, Windows, mobile) development platform :-) will be a great asset and considering that iPhone will be closed to third party developers it may have a strong advantage.