We’ve known for a while now that Angry Birds is coming to Windows Phone 7. The company has hinted at the fact on Twitter enough times, at least. Now Rovio has confirmed this in an interview with Pocket-Lint.

And the developer also gave the reason why Angry Birds is taking so long to perch on Microsoft’s fledgling smartphone OS. Rovio CEO Peter Vesterbacka said, "Let’s just say, Microsoft has a lot of lawyers."

We asked Rovio to expand on this statement, but the developer declined to comment further.

We do know that Rovio and Microsoft had a slight disagreement before WP7 even went on sale. Microsoft used an image of Angry Birds without Rovio’s consent on its Windows Phone 7 launch site to show off what apps would be on the device.

“We have NOT committed to doing a Windows Phone 7 version. Microsoft put the Angry Birds icon on their site without our permission,” the developer tweeted in response.

But that’s now water under the bridge, Vesterbacka says, and Angry Birds will indeed be coming to the device.

The developer also said a 3D version is being developed. Presumably this is for 3D mobile phones like the LG Optimus 3D, and not the previously-announced Nintendo 3DS version.