There's been a wired Xbox 360 steering wheel for years now. I should know, there's one in my closet gathering dust. There's now a wireless Xbox 360 steering wheel. Think Mario Kart's plastic wheel, only a lot more expensive.
Due out in October, and priced at $60, it's an...interesting looking peripheral. While being released with Forza 4 in mind, Microsoft claims it'll work with all existing driving games, though with the caveat that in some titles there will be "limited functionality".
While it looks like Nintendo's plastic wheel, it's not motion-controlled (no mention was made of that in the wheel's press release), as it looks like you can attach (look at the pics of the unit's bottom) it to something of your choosing instead of lugging around its own cumbersome base.
UPDATE - The wheel is indeed motion-controlled, players waving it around in the air to steer their car. Just like Mario Kart on the Wii after all, then.
It's also got haptic feedback and rumble.