As reported by C|Net:

Microsoft will offer a wireless keyboard designed for computers running the home entertainment version of the Windows operating system, the world's largest software maker said Tuesday.

and Engadget:

Yup, it’s even got backlit buttons and an integrated touchpoint mouse, and should go for about $100; in other words, we’d totally hit it.

I had the opportunity to play around with a prototype (codenamed, "Kirk") a few months ago.  Here are my thoughts:

• It feels good in your hands or on your lap
• The backlit buttons are GREAT
• It works up to 30 ft away
• The eraserhead-style mouse works great on the rare occasion you want to use it
• A master lock so that my kid won't reprogram my PC banging on it!  My washer/dryer/refrigerator/microwave/oven have this.  All major devices designed for home living spaces should do the same.

Feedback I'm sending to the team:

• IR is good, but BlueTooth would be even better IMO.  I understand why IR, it helps keep costs lower (for PC Mfrs and consumers)
• I would have put the green button further up on the r-hand side.
• A small, LED-based battery meter on the underside would be ideal.

Available in September, more details here.