I know the DLO neoprene cases have been out for about a week now, but I haven't seen any 3rd party leather cases, until now.
http://www.incasedesigns.com/DetailIpodSleeve2.php
looks pretty nice. I guess it's not a huge departure from the case that comes with the iPod, but I bought the 10GB one, and mine didn't come with one. I hear that the original ones scratch up your iPods as well. I've seen the older model InCase sleeves, and they looked pretty nice, and the price is really good. I would suggest buying from the Apple Store to save a few bucks on shipping. They don't try to rip you off on s&h costs like many manufacturers do. I bought the case, on Saturday, and it was shipped out on Saturday. The total was under $30.
http://store.apple.com/1-800-MY-APPLE/WebObjects/AppleStore.woa/70207/wo/8S1kY7Kq4Vbg202e5DaK5HOMnZM/1.3.0.5.8

...should arrive on Tuesday or so. I will post back with feedback.