Great info provided by Todd Brix on Marketplace for Windows Phone 8!
- the addition of more countries : more than 180 countries at launch
- new ways of monetization : in-app purchasing, enterprise apps-hub, SD-preloaded
- and the awesome new gen marketplace platform : rebuilt from the ground up to be more robust and scalable
You can check all the detail at http://windowsteamblog.com/windows_phone/b/wpdev/
check it out!