Finally Angry Birds is now available for Windows Phone 7, you can download the Angry Birds via the Marketplace and it costs $2.99. You can also try out the first few levels for free.
Press release below
The survival of the Angry Birds is at stake. Dish out revenge on the green pigs who stole the Birds’ eggs. Use the unique destructive powers of the Angry Birds to lay waste to the pigs’ fortified constructions. Angry Birds features hours challenging, physics-based demolition gameplay, and lots of replay value. Each of the 165 levels requires logic, skill, and brute force to crush the enemy. Protect wildlife and play Angry Birds!