There is a tie for the Manhattan Beach (single family) home listed the longest, that sold in September.
926 N. Rowell Avenue (see Oct 2nd post for September Lowest $ Manhattan Beach Home Sale) was listed on 12/1/09 and sold on 9/27/09.
328 16th Street (pictured) was listed on 12/3/09 and sold on 9/29/09. This is a gorgeous, new, walkstreet home, close to the beach and downtown. It was designed by Louie Tomaro and built by Mike Davis Custom Home. It has 4 bedrooms, 4.5 bathrooms and all the high-end features & finishes you would expect of a new, luxury home at the beach. The original listing price was $3,643,000. It sold for $2,950,000.