The U.S. Postal Service (USPS) said today that florist and gift shop giant 1-800-Flowers.com is the launch customer for the USPS' same-day delivery service, which starts today in pilot form in San Francisco.

The service, called "Metropost," will run in test mode for a year and only in a 49-mile radius in and around San Francisco. After that time, USPS can apply to expand its scope or kill it altogether if demand doesn't meet expectations.

Based in Carle Place, N.Y., 1-800-Flowers.com will utilize the service to offer same-day deliveries of foods and gift baskets and towers, USPS said in a statement. The company has offered same-day floral deliveries since its founding in 1976. John G. Friess, a USPS spokesman, said more companies are preparing to sign up for the program.

No more than 10 e-commerce companies can participate in the pilot. Each participant must have at least 10 physical locations of some type nationwide, with one or more in the San Francisco area. Through the end of December, only 200 packages a day can be tendered. The package restrictions can be lifted if USPS decides to increase its capacity supporting the service.

Users must live within the area designated for delivery. Cutoff times for orders are between 2 and 3 pm, with packages to be picked up after 3 pm and delivered between 4 pm and 8 pm. USPS has developed a separate delivery network dedicated to the implementation.

Due to laws governing a USPS service rollout, annual revenue during the test phase cannot exceed $50 million. USPS' total annual revenue is approximately $66 billion.

The pilot program launches the day that UPS Inc., which is both a USPS competitor and partner, is expecting an all-time one-day record for deliveries. Atlanta-based UPS expects to deliver 28 million packages worldwide, nearly doubling its average daily delivery count of 15.6 million packages.