Online ecommerce giant eBay today announced “Project Echo” at the eBay developers conference, which will allow developers to create applications for sellers that will run inside the eBay Selling Manager. Previously, third party applications built for eBay via the site’s API could only run off site. Project Echo, which will probably launch sometime in 2009, can be thought of in terms of Salesforce’s AppExchange platform. But is better integration with third party seller tools really what eBay needs to do to keep sellers satisfied?

According to Computer World, eBay has 700,000 merchants who subscribe to their Selling Manager, and 70,000 developers currently working with their API. eBay’s senior director of mobile platform and disruptive innovation, Max Mancini, described Project Echo as taking the company’s app development platform to the “next level.”

But what we’ve heard from sellers over the past couple of weeks doesn’t lead us to believe that fancier selling tools will be enough to keep many of them on the site. What has sellers leaving the site is changes in policy that many sellers feel have negatively affected their ability to sell on the site, or unfairly given preferential treatment to corporate partners.

eBay has appeared to be taking steps over the past six months to transition the company toward an emphasis on fixed price selling over their traditional auction format. If sellers really are leaving the site, that spells trouble for eBay, where fewer seller options, no organized product reviews, and no “Amazon option” that offers free shipping means eBay will face difficulty attempting to compete seriously in the fixed price market.

While better integration of seller tools will certainly be a welcome change for many sellers, it by no means fixes the potentially major problem eBay is facing: the rift that has developed between management and top sellers on the site.