The App Exchange is a service which focuses on developers who reside outside the realm of supported countries for application submission into the Windows Phone Marketplace. They allow these developers to register an account and submit their application to the team for Marketplace forwarding on the developer's behalf. Each submission costs $19.99 and a re-submission sets one back at $9.99. A 'coming soon' service is none other than device unlocking, which is priced at $49.
Supported countries include Bangladesh, Brunei, Cambodia, Indonesia, Laos, Macau, Malaysia, Mongolia, Myanmar, Philippines, South Korea, Thailand and Vietnam. Please note however that WPCentral is not advising developers to use this service. Should something go wrong, don't shoot the messenger. With all third parties, one must be aware of possible problems that could arise. Always read the Ts and Cs and be sure to contact them for more information prior to signing up.
A pretty in-depth walk through can be found using the link below at MSDNPhilippines.