I wanted to briefly talk about the two articles that Wizards posted about the new Xbox game. (The game doesn't have a deck editor if you can believe it and is an introduction to the game of Magic.) The AI seems pretty good. The game starts on medium difficulty but the user can change it to make it more challenging.
The article mentions that the AI will attack with a 1/1 into a 2/2 if it is holding Giant Growth and an untapped Forest. And "there's the time it attacked with a bunch of green creatures, let me block, and only then used Elvish Piper to drop a Roughshod Mentor into play and give everything trample." While these examples wouldn't win a pro tournament they are still impressive for a computer. While effectively using Giant Growth isn't rocket science the key idea is that the Xbox AI can use other cards like Giant Growth without additional programming.
One of the articles mentions that the AI can only look ahead for one combat phase. For example the computer might attack with all of its creatures just to lose when the human player attacks with his creatures. I find that this scenario occurs often in the games that I play. MTG Forge's AI also makes this error because the combat logic is relatively primitive.
The user interface is separate from the rules engine which is always good. One of the articles even shows the internal representation of Angel of Mercy. While I think using XML for Magic cards is cumbersome, it is interesting to see how a "commercial Magic" project does it. (You can right click and open the gif below in a new window in order to see it more clearly.)
p.s. It is great to see Lightning Bolt again in Magic 2010. I didn't think it would ever be reprinted.