Weta has announced that that they are doing work on George Miller's Mad Max: Fury Road. Here is what the site says in an official statement:

We're thrilled to announce our involvement with Mad Max: Fury Road, a long-awaited continuation of the Mad Max suite, the last installment of which, Mad Max Beyond Thunderdome, premiered 25 years ago.

As with previous Mad Max movies, George Miller is the director and Weta is very excited to be working with George on conceptual design, Specialty Make-Up FX, Costume and Dummies. The movie is currently scheduled for a 2012 release.

Now comes the question of when this much anticipated fourth film in the Mad Max franchise will shoot. According to The Australian, since they are now going to make two films instead of one (the second one titled Mad Max: Furiousa), this major project will not go in front of the cameras before February. They report:

The reason for the postponement is unknown, although recent internet reports indicate that director George Miller is overseeing the shooting of not one but two Mad Max films from the same production. It is believed this development has caused some screenwriting and casting problems. The office of the film's production company, Kennedy Miller Mitchell, would not confirm or deny the postponement from an expected November start date to next year.

Nothing has been officially announced that these films are postponed from their November start date.

Evan Jacobs at Movieweb
Evan Jacobs