Online classifieds service Oodle is reporting decent growth in the first month of 2009 with over 10 million visits (both Quantcast and Compete reflect a significant traffic surge). Add to that the fact that social networking juggernaut Facebook has selected the company to power its classified listings application and you know they’re on to something over at the San Mateo, CA-based startup.

Its investors seem to agree, as they have just injected more capital in Oodle: Greylock Partners, JAFCO Ventures and Redpoint Ventures are adding another $5.6 million to the startup’s war chest, bringing the total amount invested in the company to $21.6 million.

Oodle is already powering the classified listings for MySpace, and the roll-out for the Facebook Platform is supposed to start this quarter, effectively replacing an in-house solution (Facebook Marketplace) in favor of a product developed by an outside company, as Facebook CEO Mark Zuckerberg explained in a recent interview with Michael Arrington.