North America’s summer movie season began this weekend with a big success for a superhero tentpole and a disappointing start for the latest 3D release.

20^th Century Fox’s “X-Men Origins: Wolverine,” launched the season by winning its opening weekend with $87 million. That is the second biggest start for an X-Men franchise film. “X’Men: The Last Stand” opened in 2006 with $102.7 million, although that was released over the four-day Memorial Day holiday weekend.

In second place this weekend was Warner Bros.’ romantic comedy “Ghosts of Girfriends Past” with $15.3 million.

The success of “Wolverine” supports expectations that this summer will be one for the record books. Additional tentpoles expected to drive big box office revenues this summer include “Transformers: Revenge of the Fallen,” “Harry Potter and the Half Blood Prince,“ “Star Trek” and “Angels and Demons.”

Digital 3D will be a key area to watch this season. The summer of ’08 had only two 3D releases: “Journey to the Center of the Earth,” which topped $100 million; and “Fly Me to the Moon,” which brought in $13.6 million. A year ago there were also fewer screens.

This weekend, Lionsgate’s digital 3D title “Battle for Terra” made its debut, while Dreamworks Animation’s 3D “Monsters Versus Aliens” remained in theaters.

Computer-animated “Battle for Terra” opened in 1,162 2D and 3D theaters, but finished in 12^th place for the weekend with just over $1 million.  In contrast, last summer’s animated “Fly Me To the Moon” opened with $1.9 million in just 452 theaters.

The 3D winner for the weekend was animated “Monsters Versus Aliens,” which in its sixth week collected another $5.8 million, bringing its domestic gross to $182.4 million. “Monsters” is the highest grossing movie of the year so far in North America.

A few 3D observations:

–Content is still king. Despite its strong buzz, digital 3D was not enough to drive big box office for “Battle for Terra.”

–Screen count: Estimates suggest that there are nearly 1,500 3D-ready theaters in North America. Yet still to come this summer is a steady slate of digital 3D titles including Disney/Pixar’s “Up” (May 29), Fox’s “Ice Age: Dawn of the Dinosaurs” (July 1), Disney’s “G-Force” (July 24), Disney’s “X-Games 3D The Movie” (Aug. 21) and Warners’ “Final Destination: Death Trip” (Aug. 28).

“Monsters” is still performing in its sixth week in release. Will the slate of 3D titles that will be sharing screens this summer prompt an increase in 3D theater installations?