The Windows Mobile app store (Windows Mobile Marketplace) is now accepting developers, who can enter their info and upload apps at will. All they need is a credit card with $99 and a Live ID (Hotmail or passport account). The previously mentioned amount of cash is the annual fee, that you’ll also pay next year and so on.
Microsoft also mentions that developers who hurry up and become part of this service will have an advantage, as they’ll be the first to market their apps and earn more money. As funny (or ironic) as it may seem, the Marketplace seems to have issues with non-Microsoft browsers like Firefox or Google Chrome, so IE is recommended for use.
This app store will only be available on Windows Mobile 6.5 devices, that will be available from September 2009. More details can be found here.