With a new application framework entering open beta early next year, eBay is working to build a kind of 'open' market for both developers and vendors to earn money, as a key eBay developer told BetaNews Tuesday.

A private beta of eBay's Project Echo will commence in Q4 2008, limited to participation among five ISVs including research tools provider Terapeak and CRM service provider Hosted Support. That will be followed by an open beta early next year and commercial availability by mid-year. This news Tuesday from Kumar Kandaswamy, senior director for platform strategy of the eBay Developers Program, in a briefing for BetaNews.

"There's been a lot of talk in the industry about 'opening up' this and that," Kandaswamy said. "But we have two points of differentiation. One is simplicity. The other is that developers can make real money with us."

Project Echo's public beta will be open to all interested developers, the senior manager told us, with just a couple of provisos: "First, all [developers] must be willing to provide 30-day free trials of their products, both during and after the beta. Second, they must clearly call out the subscription price of their software for sellers."

Through Project Echo, developers will be able to integrate their existing applications directly into Selling Manager and Selling Manager Pro, two eBay applications that already count some 700,000 eBay sellers as subscribers, Kandaswamy told us. That should enable sellers to subscribe to and start using their tools directly on eBay's site.

Historically, sellers interested in trying out new third-party applications have had to go to a special section of the site known as Solutions Directory, and then click over to the ISVs' sites.

Kandaswamy also acknowledged that eBay faces growing competition from other Web sites in luring application developers.

eBay is accessed by literally millions of buyers and sellers worldwide, according to the strategy manager. At the moment, there's a push within the company for the creation of new and sophisticated tools that can help sellers do a better job of marketing their wares.

But eBay has already attracted some 70,000 third-party developers since the launch of the Developers Program eight years ago, he noted. Moreover, much of eBay's traction with developers has happened over the past year, with 50,000 of those developers hopping aboard just since then.

A total of 4,800 of the 12,000 third-party applications built for eBay have been created over the past 12 months, he elaborated.

One of the latest third-party applications built for eBay assesses the buying behavior of individual buyers, in order to make recommendations to sellers about which buyers they should target. Another leverages current market data to help guide sellers in making decisions about which products in their inventories to focus on, and what prices to charge, Kandaswamy said.

He credited the recent expansion of eBay's development environment for much of the growth in application development activity.

Instead of being limited to .NET and PHP, as in the past, eBay developers can now work in JavaScript, Flash, and Flex, as well. Meanwhile, eBay has also added integration interfaces for SOAP and XML.

Aside from a Web-based SOA platform for application integration, Project Echo also calls for the "opening up" to third-party developers of several APIs -- including "eBay Client Alert" -- that were previously available only to internal developers.