If it works then I think it would be a great idea. I've already seen advertisments for Android phones that claim a high number of apps, but without an Android device you can't even browse their app store to see what is available. This is a very poor strategy I think. If I could browse the Android app store on my PC that might make me want to buy an Android.
I think the carriers would have to focus on one OS though. Nobody wants to find an app that they like and discover that it doesn't work on their phone. The big advantage Apple has is that all apps work on their phone, maybe even all versions of their phone. And they have ONE software development kit to deal with too.
In the past I've had several PocketPC-based PDA's, and now a WM6.1Pro phone. I've been interested in developing my own apps, I've searched the net for programming languages, I've found numerous ones, but none that I was able to get into. So besides a common platform to develop apps for, they need to provide one and only one decent software development kit.
What I want- a phone that works. ALL of the features work, the GPS, the voice-dialing, apps, wifi. I want a SDK that will run on a PC and make it easy to develop apps. I want a phone that will easily connect to a PC. I have a fairly new Samsung Epix that cost a lot of money when new, and I get none of those features with it. About 4 more months and I get to change phones. I would get an iphone if their SDK would run on my PC, but they can't allow that.
The iphone has a big momentum going, but it is not the leader in market share. I read that Blackberry has more units in the US, so it is possible to compete against the iphone if you really want to compete, and that means more than just making cutesy TV ads.