Thanks to John Stowers’ link drop (and his offhand remark that someone could "use this as the basis for window previews in libwnck") and a rainy Sunday, I’ve now added some XComposite / XRender blingfactor to SuperSwitcher (yeah, SS first, maybe libwnck later, once I actually understand how all this X voodoo works). In a word, thumbnails:
Compare that to the version 0.1 screenshot:
It’s (more than) a little buggy at the moment (e.g. it doesn’t show minimized windows’ contents, or those from different workspaces, and it doesn’t speak XDamage events), but if you want to play with it, the code has just hit the SVN repo.
If you don’t recognize the video playing in MPlayer, then get your eyes onto some sweet, sweet Chaser.