Or like how my girlfriend got a iPhone 4 a month before the 4S (and Siri) came out?
Stop acting like Microsoft is the big bad wolf in this scenario.
Actually, Microsoft is the big bad wolf here. Siri is just one feature of the iPhone 4S. With Windows Phone, a WP8-compatible application will not work at all on WP7.5 handsets. It would be akin to all new apps in the iTunes store not working with the iPhone 4.
I know this decision has pretty much ruled out me wanting a Nokia Lumia 900.