I don't see how that saves battery life really. Oh wait, so it's not like multitasking at all really? Like I still couldn't open an app to stream music from pandora or last.fm, close it into the backround and check my email with it playing? I could just switch between them more quickly? I think that's how MS is planning on doing it as well...shit will be suspended for some apps, but it can't actually be running.
It's better than nothing, but it really wouldn't be so bad if some things could run in the backround, you know what I mean? Or at least have the option? People could choose battery life or functionality like that.