During the Comic Con Event at San Deigo, David Jaffe confirmed that there will be a Twisted Metal beta coming very soon. He also revealed Twisted Metal's Opening Scene during the Confernce.
If you are only interested in the intro it starts at about four minutes in the video, But the entire vid is quite enjoyable especially when Jaffe jokes about Anonymous. (3:36-3:43)
Please also note that David Jaffe has stated that the opening movie is only about 85% finished. :)
http://www.dualshocknexus.com/2011/07/twisted-metal-opening-intro.html