Published online today in Nature AOP (advance online publication):
Acceleration of the rotation of asteroid 1862 Apollo by radiation torques
Mikko Kaasalainen, et al.
doi:10.1038/nature05614
First paragraph
Supplementary information
And there will be an accompanying News and Views piece:
Asteroids: Spun in the sun
William F. Bottke
doi:10.1038/nature05711
Full text
See also the related press release: Scientists find a solar-powered asteroid.
Note also a related paper that will be published online tomorrow in Science Express.