New Kennedy Motorcade Footage...

... not of the assasination itself, but taken shortly before the shooting:

The film was donated to the Sixth Floor Museum in Dallas and released this week, according to Deborah Marine, public relations manager for the museum.
"We've been amazed at the interest," Marine said. "This started out very much a local and regional story in North and East Texas. It's mushroomed. We've had media inquiries from all over the country, and it's taken on international proportions with calls from BBC, Australia and BBC Latin America."
The public release of the film, stored for more than 42 years in a drawer in the owner's home, created a nationwide buzz Monday and overwhelmed the Web site of The Sixth Floor Museum at Dealey Plaza. Marine said the museum's Web site, www.jfk.org, can handle 1,500 hits per minute. The Web site went down Monday soon after an Associated Press wire story announced the release.

The linked article includes a link to the footage itself.