Product Details from the site:

Mac + PC
Wi-Fi 802.11 wireless*
40GB hard drive for up to 50 hours video
Apple Remote
Ships: February
Free Shipping
$299.00

Any time is prime time
Now there’s always something good on TV. With Apple TV, you can enjoy movies, TV shows, music, and podcasts in your iTunes library, plus photos and movie trailers, on your widescreen TV — wirelessly, from your Mac or PC.

Download
Ready to be entertained? Any time day or night, simply download what you want to watch or listen to from among millions of choices on the iTunes Store. Then let Apple TV do the rest.

Sync
Apple TV automatically grabs the digital media on your computer and makes it available for you to enjoy on your TV. Best of all, whenever you add something new in iTunes, Apple TV updates automatically.

Watch
Thanks to the intuitive interface, finding what you want to watch is as easy as navigating a few simple menu items using the included Apple Remote. Just a few clicks and you’ll be enjoying all your favorites from the comfort of your couch.

It remains to be seen if this is any better than Sling Media’s Slingcatcher, which will be available for just $200 to Apple’s $299.