Wow. Where to begin
The one thing PC OS's lack is a simple messaging/contact app. Because of this, I don't even use my PC as contact database except for emails, I use my phone. This could really could be a winner for BlackBerry.
That said, Blackberry has an abysmal record of PC interface software design. While the concept is often good, the software itself has always been buggy. Let's hope they get it right this time.
A fully seamless phone/PC integration is surely the next evolutionary step. No, Windows, I don't mean you.