The Gates Cambridge Scholarship supports one to four years of post-graduate study (including a second Bachelor's degree, if appropriate) in any field at the University of Cambridge.  Applicants must show exceptional academic achievement, potential for scholarly development, and a desire to use their education for the benefit of others.  Citizens from any country other than the UK are eligible.  Students apply to the appropriate graduate program at Cambridge and to the Gates Scholarship in the same form; however, admission and the award are controlled by separate bodies.  (Bates First Submission mid-September, External Scholarship deadline mid-October)

See the main Gates-Cambridge Fellowship website for further details: 
http://www.gatesscholar.org/