Fact and fiction again meet in an article on CNN. Early designs for Star Wars ships, likely to be seen again in Episode II, included a solar sail. This concept is being developed in the real worl:

Amateur space enthusiasts plan to send a solar sail prototype into suborbital flight this summer, following successful repairs to the experimental spacecraft after a test mishap.

The Planetary Society, the largest private group of space exploration supporters in the world, said the windmill-shaped vessel will use solar power to propel itself through space.

The solar sail should launch aboard a modified Russian intercontinental ballistic missile from a Russian submarine in the Barents Sea. After the suborbital trial, an orbital flight will take place later this year, the Planetary Society said.

The craft was expected to fly earlier this year but suffered serious damage as Russian technicians conducted pre-flight tests in April. The re-entry shield inflated inside the closed capsule and pyrotechnic devices meant to separate sections of the craft accidentally fired. The snafu snapped cables and bent portions of the sail platform.

Visit the link above for more!

UPDATE
Dragunov gives us this update:

Not wanting to blow anyone's mood over seeing this craft in EPII, but the concept has been around for some time. The two most notable instances that immediately popped into my mind were the solar sailer from Disney's "Tron" and from the novel "The Mote in God's Eye" by Larry Niven. Both were pre-1985, so I'm sure the designs for such a craft were around for much longer. There was even an episode of Deep Space Nine that featured a solar sailer (this is only a point, not an endorsement of the show). spoilerIn its use as Dooku's craft in EPII, I can see where Lucas would prefer to use an elegant, (presumably) non-militaristic looking vessel for a sith lord of this time period in the Star Wars universe. It is grand in a manner that even a Star Destroyer cannot match. The design, for Dooku, would bespeak an inner strength and fearlessness of the universe (they are, by their design, somewhat frail in appearance), yet instill a sense of awe upon seeing his arrival. I can't wait to see this style of ship after ILM has a chance to play around with it.