Finding the whole 'carriers and manufacturers can have their own app store section' situation on Windows Phone 7 quite interesting.
Basically, the carriers and manufacturers of the devices can offer their own exclusive free/paid apps to their customers only, and have a dedicated category in the Marketplace for such. Furthermore they get access to the native SDK so can do things way beyond what apps built with the public WP7 SDK can do (i.e. DLNA streaming, augmented reality, hardware access, etc).
For example, LG offers an application on the Marketplace (that only their phones will see) that allows you change APN/carrier settings to match any market in which LG has a device; something you can't do with the standard APN settings on Windows Phone 7. There are definitely some other very cool free apps from LG;
You can also re-download any of the bundled apps (that you may have deleted when buying the phone).
It's a fascinating solution to the carriers-have-no-power situation on iOS, and carriers-have-too-much-power on Android. I think it's the perfect compromise.