As in llooooonnnnnggggg. Santa Monica to Manhattan Beach, Oct 2010
Full is 12.6 miles, but there will apparently be relays and shorter options, to be announced soon. Not sure if you HAVE to stop at the indicated spots for the long swim, that makes it easier and harder in a way.
Only link I know of is a facebook page, not sure if you have to be a FB member to view it
www.facebook.com/.../344925859854