@Bass: There's no guessing involved at all. A process has work to do or it doesn't. Allocating resources to it, taking it account all the various factors (what is the user doing, how long has it waited, what else is going on, etc), is exactly what the OS is doing today. The only difference is the idea that process lifecycle is something the end user has to manage instead of the system and there really is no rational reason behind that. If a push-service in the cloud is capable of notifying that an end user has received new email, why should the end user have to manually start a process to receive it and notify them? Why doesn't it just happen?
@Sven Groot: Yeah but the idea of "grouping" on the Taskbar only works if you're working on one single task at a time (even if that's one task involving multiple applications). Speaking personally I'm rarely lucky enough to be in that position and am constantly "real world multitasking" and having to move between different real world tasks, each of which involve multiple (sometimes overlapping) sets of applications. The Taskbar is hopeless at that, it doesn't really offer anything to help other than it's basic functionality as an application switching mechanism. ALT-TAB and the Metro list thing are far, far more useful in that regard because both put the focus on what I've been using most recently.