Microsoft announced this morning a handful of tweaks and changes to its Windows Phone Marketplace, many of which promise to make it easier for developers to publish in the now five-month-old digital storefront. The company also provided a look into the purchasing behavior of users, saying that nearly 1 in 10 downloads of a trial for an app or a game results in a sale.

One of the biggest changes centers around application distribution and publishing. Microsoft announced plans to launch a new Global Publisher Program, aimed at helping developers get their games in more markets.

"This program will enable developers worldwide to work with a Global Publisher to submit apps to the Windows Phone Marketplace," Todd Brix, Microsoft's senior director of mobile said in a post on the Windows Phone Developer blog. "Developers from countries and regions all over the world can now submit apps and games to the Windows Phone Marketplace."

That system, Brix explained, would have developers providing publishers with their applications, who would then submit them to the Marketplace and set the price. These publishers would also be responsible for ensuring the applications made it through Microsoft's certification process.

The Global Publisher program is joined by a handful of policy changes, one being an acknowledgement and clarification of developers' use of open-source licensed tools in their games and applications.

"The Marketplace Application Provider Agreement (APA) already permits applications under the BSD, MIT, Apache Software License 2.0, and Microsoft Public License," Brix said. "We plan to update the APA shortly to clarify that we also permit applications under the Eclipse Public License, the Mozilla Public License, and other, similar licenses, and we continue to explore the possibility of accommodating additional OSS licenses."

Last month a clause in the APA had come under fire for promising to ban any apps licensed under the GNU GPL v3, GNU Affero GPL v3, and GNU Lesser General Public License v3. Microsoft had responded by saying that the policy document was continuously being revised, and that the company would be "exploring the possibility of modifying it to accommodate additional open-source-based applications in upcoming revisions."

Other policy changes include a move to raise the limit of complementary app certifications that are offered for nonpaid applications from 5 to 100, as well as a change that makes leaving contact information for application support an optional affair. Brix explained that the mandatory inclusion option had slowed down the certification process.

Along with the update on the license, Brix said the company has seen great success with the implementation of trials for games and applications. These let users download and use a paid application before buying it, and have resulted in both higher total download numbers than applications without the feature, and higher sales.

"Nearly 1 out of 10 trial apps downloaded convert to a purchase and generate 10 times more revenue, on average, than paid apps that don't include trial functionality," Brix said. Those who make the jump from trial to a sale also do it in short order. "More than half of trial downloads that convert to a sale do so within one day, and most of those within 2 hours," Brix continued.

The trial feature has proved to be one of the big differentiators among the mobile app marketplaces. Google offers refunds for applications on the Android Market, but there is currently no mechanism to download a paid app without first plunking down a payment. Apple's approach thus far has been to allow free applications to offer full functionality through in-app purchase.

Brix also shared some preliminary results from developers using the company's Ad Control platform, which lets developers stick advertising in their applications. Brix says 95 percent of apps with ads on the Windows Phone Marketplace are using Ad Control, and that ad impressions have gone up 400 percent in less than three months.

The Windows Phone marketplace now sits at 9,000 applications, and 32,000 registered developers who just began getting payments for their applications at the end of January. Microsoft has not yet disclosed the total amount of those payments. As a refresher on the platform's momentum, below is our graph of the number of developers and applications, as announced by the company since launch. Worth taking into account are that both numbers are likely to shoot up as Microsoft's strategic partnership with Nokia progresses.