Richard Branson isn’t letting any grass grow under his Virgin America, thats for sure; he’s just announced a new air fare sale, to coincide with the airline’s new flights between San Francisco and Washington D.C. Take a look at these prices (prices are one-way)…

• $119 Washington Dulles (IAD) — Los Angeles (LAX) (non-stop service starts 10/24)
• $129 Washington Dulles (IAD) — San Francisco (SFO) (non-stop service starts 9/26) $39 Los Angeles (LAX) — San Francisco (SFO)
• $139 New York (JFK) — Los Angeles (LAX)
• $139 New York (JFK) — San Francisco (SFO)
• $44 Las Vegas (LAS) — San Francisco (SFO) (service starts 10/10)

Tickets go on sale today at Virgin Americas website (or call 1-877-FLY VIRGIN), but you must act quickly; tickets must be purchased by Sept. 27th and there is a 7-day advance-purchase requirement. The tickets are good for travel through February 12, 2008.

Virgin also announced it’s adding flights to the following routes:

• San Francisco Las Vegas
• San Francisco - Los Angeles
• New York Los Angeles

It only took about 2 shakes of a lamb’s tail for the major legacy airlines to match Virgin America — here’s to hoping this little transcontinental airfare feud lasts a while …