At long last, the MySpace Developer Platform is open for business. News Corp’s social networking behemoth is launching a dedicated site for developers Tuesday and it will go live to all audiences in a month.

Says MySpace COO Amit Kapur: “We want to make sure that we build a rich platform for monetization for the developers.” That’s jargon for the promise that MySpace will make widget-makers money.

That’s a significant turnaround for the site, which just one year ago considered third-party developers to be parasites, sucking away traffic and ad dollars. While Facebook embraced widget makers, MySpace (NWS) originally tried to control them and was accused of booting them from the site. That changed, though, as Facebook gained a major boost in traffic and valuation from the applications that outside developers launched. Speaking at the Web 2.0 conference last fall, MySpace co-founder Chris DeWolfe promised to open the site up.

The MySpace Developer Platform will be a social networking hub for creators of applications that run on the site. The site will host a blog, and it will give developers the tools to build their applications in a live environment. It will also offer forums, sample code, and an opportunity for developers to test their applications on pools of five member profiles in advance of release. The platform will support OpenSocial, the Google initiative to establish a common set of tools for developing widgets so they work across platforms, right from the start.

MySpace has also promised to help developers profit from their widgets. The site plans to offer developers access to much of the information the company has gathered in testing hyper-targeting strategies with advertisers and its experiment in self-serve advertising. “It’s a long-term play for us,” says Kapur, a MySpace veteran who assumed the COO post last week. “If we can tie those technologies into the developer platform environment, we are going to help them make money and we can build a new business for ourselves.”

“It’s an important evolutionary step for Myspace,” says analyst Rich Greenfield of Pali Research. “They need to harvest the power of developers across the Internet. It will be interesting to see how attractive this platform is compared to the Facebook platform.” With an eight-month lead, Facebook has a rich developers’ community. But with 69 million users logging onto their profiles in December, MySpace offers a lucrative and attractive environment for widget makers.

The challenge for MySpace will likely be attracting developers by giving them access to marketing data without compromising member’s experience. Before MySpace was a place for developers, it was, after all, “a place for friends.”