Mobile app store Pocketgear announced today that it’s relaunching as Appia, a platform to enable mobile operators, manufacturers and portals to deliver app stores of their own.

The company is shifting away from being a destination site and will instead focus on using its catalog of 140,000 paid and free apps to power third-party app stores globally. It currently hosts apps across all major platforms except iPhone OS — including Android, BlackBerry, Symbian, Java, Windows and WebOS — and supports 3,200 different devices.

The move is likely a wise one for Appia, which describes itself as “the largest open app marketplace in the world.” Mobile apps are increasingly becoming a hot commodity, but it’s difficult for independent app stores to compete with stores like the Apple App Store, Android Market and BlackBerry App World. Appia will be able to take advantage of the demand for apps by letting any company create an app store of their own.

The company says that it powers app stores for more than 40 partners at the moment, including “four of the world’s top five handset manufacturers, three of the top four mobile operators in the U.S., three of the top 10 mobile operators globally, and leading media and ecommerce companies.” Current customers include Samsung, T-Mobile, AT&T and Verizon.

Appia has also launched a developer portal for developers to upload their apps for distribution in its app library. Since Appia powers multiple app stores, developers have a chance at getting their apps on several stores and potentially earning more money in the process.

The Durham, North Carolina company scored $15 million in funding last August. It also acquired smartphone app company Handango earlier last year.