The Windows Phone Marketplace has recently gotten a mobile game that is a close substitute for Draw Something. The app is called Draw and Guess, it'd very new to the Windows Phone marketplace and it requires a few more layers of polish compared to more established apps like Duudle. The reviews for Draw and Guess are not favourable, Windows phone owners who buy this app are looking for a substitute to the incredibly popular Draw Somethign game and they're using Draw and Guess to tide them over until OMGPOP decide to bring the game over the WP7.
The Windows Phone Marketplace has been growing at an acclerated pace (although it's still nowhere near as full featured as Apple's App Store and even Android store), but its a sign of more exciting apps to come, kudos to Microsoft for putting in time, effort and money into attracting developer to support their platform.