Okay, so I'm just a little behind on this addon. Just for kicks, I downloaded the Peggle addon last night. This isn't a review, per se, but it is a nice little addon. There's a single-player mode that's just like the non-wow game. You get to choose one of two people (that basically decides your super ability). And it's just like one of those dumb online flash games that suck you in for no reason. (That wasn't meant to be negative, that's just how I classify them.)
They've made a lot of intelligent choices for designing the game. From the way it will automatically go away when combat starts, to the way that it is sort of grayed out and less protruding on the screen when your mouse is elsewhere, it really shows that they put a lot of thought into it. You can even brag about your scores by a Peggle announcement in different chat channels (only tried Guild). There's also a talent tree. How Wow can you get? lol.
I could totally see the benefit of having this addon. Since there's generally at most maybe 5 people in a 25-man raid that are doing something pre-raid. 1 person is deeply involved explaining strategy, maybe a couple are listening because they don't know the fight, a couple more are listening to add to anything the raid leader forgot, and the rest? The other 20? They can be playing Peggle. Or maybe 2 people are actually looking to fill the PUG while the other 18 are playing Peggle waiting for 5 more people to magically join.
The only problem for me is this: I'm usually the guy explaining the raids. And if I'm not, I'm usually listening to make sure nothing was missed. And if I'm not doing either of those things, I'm talking with my wife. So, after one night of one heroic 5-man TOC run, my wife suggested that I probably shouldn't get hooked on a game within a game. I wholeheartedly agreed with her and uninstalled the addon after getting off last night.