The store is actually a free application from the online marketplace PocketGear. In fact, it really is just a mobile version of PocketGear that delivers apps directly to the phone. Previously you'd have to take part in a rather clunky process to get new apps onto your device, even choosing a delivery method: SMS, email or download to a real PC and sync.
It gives users the ability to Browse and download over 2,500 apps & games right from your Windows Mobile® device. Plus, download hundreds of free apps without spending a dime. The App Store supports over 950 Windows Mobile® devices, from the Samsung Omnia i900 to the HTC Touch Diamond.