Dreamworks Animation’s debut stereoscopic 3D title “Monsters Vs. Aliens” raked in another $8.5 million at the US box office this weekend, helping bring its domestic gross to $174.8 million and allowing its international box office to cross the $300 million mark. The film opened March 27 in the US and is the highest grossing film of 2009 to date, both in the domestic and worldwide box office.

A second 3D release, Focus’ “Coraline,” also sits in the US box office’s top 10 for the year so far. At number nine, the Henry Selick-directed stop-motion title has earned just shy of $75 million.

For other recent 3D releases: Lionsgate’s “My Bloody Valentine 3D” has taken in $51.5 million in the domestic market; and Disney’s 3D only release “Jonas Brothers: The 3D Concert Experience” earned $19.1 from roughly 1200 3-D screens.

In contrast to the Jonas release, Disney’s 3D “Hannah Montana/Miley Cyrus Best of Both Worlds Concert” earned $65.5 million on only 650 screens in 2008. What factor or factors caused this difference? Was it the popularity of Miley Cyrus? Was it the fact that the “Hannah Montana” movie opened the day after the live concert tour wrapped, and was therefore considered more of an “event?”

–In this weekend’s US box office news, Screen Gems’ Beyonce Knowles starrer “Obsessed” led the pack, opening with $28.5 million.

But perhaps more notable is that “Earth”—the debut documentary from Disney’s new Disneynature banner—finished in the No. 5 slot with $8.6 million for the weekend. The movie opened last Wednesday and the five-day cum is $14.2 million. The result seems underscore the potential of digital documentary/alternative content. Disneynature launched in 2008 with a slate of nature documentaries. At the time, Disney chairman Dick Cook said 3D was a possibility for future Disneynature releases.

“Earth” is the first title from producer-director Alastair Fothergill (BBC and Discovery Channel’s “Planet Earth”), who has multipicture deal with Disneynature.

Announced productions under the new banner include “Oceans” and “Orangutans: One Minute to Midnight.” Both are slated for a 2010 release.