Many Vendors waiting to see
The problem (for Microsoft) is that many of the hardware and telecomm vendors have already invested heavily into supporting and promoting the iPhone and Android platforms. Microsoft being so late to the party means that they are likely going to have to monetarily underwrite getting these same vendors to support their products to get them out on the market.
There is also the slight problem with Microsoft's heavy-handedness in licensing. Microsoft is going to have to back off and not insist on a lot of royalties from these same vendors (like they have in the past) because they are the newcomer rather than the established player here.
In short, it looks as if Microsoft might actually have a product that can go toe-to-toe with Android and iPhone. The question is: will Microsoft try and continue business as usual or truly approach this as a new market they have to win?