I think i was just saying (to many comments above and beyond) that alt-tab and the startbar (with running icons) is basically just - another side of apps that are not yet open. So why separate the 2?
The start menu really should indicate what's open b/c the same tile can't both open a new instance of an app and resume an existing session. There has to be some visual cue to separate the two. I'm okay with the desktop taskbar representing what's open only within the desktop for the sole reasons that metro apps are full screen - the moment you click on one in the taskbar, you'll be thrown out of the desktop.