There's a new update for Xenia (opens in new tab), the free and open-source Xbox 360 emulator, and it looks like framerates and stability are up in several games. There are still plenty of weird glitches here and there, as the footage of Fable 2 in particular shows—at one point you can see through the floor, and the framerate stays at 15 fps. And while Lost Odyssey looks fine, I don't know what's going on with the audio.
Still, these new videos from YouTube channel John GodGames Emus (opens in new tab) definitely show some console exclusives running better on PC than they have before. Gears of War 2 (which is a great game for blasting through over the course of a weekend with your brain in neutral) looks like it's almost there apart from some occasional slowdown, and Silent Hill: Downpour (which has some freaky sidequests even if the main storyline's nothing to write home about) seems totally playable. I've never played Asura's Wrath but it's here too. Which is nice.