If I'm not misunderstanding your idea, this already exists, and I have it installed currently. In my general use, though, I'm at least as likely to have one or more apps open as I am to have it on the home screen, so I don't really mind tapping the switcher button. Aside from the extra tap, I think the notifications are quite elegant. But anyhow, yes, there is a widget for this, so please try it out, and if it works for you, you should probably close the Brainstorm thread Cheers