Read it and weep, Oxbridge!
The Ivy League is luring record numbers of talented British students away from applying to Oxford and Cambridge. I can tell you from personal experience that there is an entire British diaspora in the Ivy League! Indeed, some of the professors are escapees from Oxbridge.
Anyway, I'm in a hurry tonight and can't find my archival post from earlier this year, but the latest international educational rankings are dominated by American schools. Indeed, if memory serves, the top 10 schools are all American universities (with many Ivies) with the exception of the UK's Cambridge and Oxford. A little competition is good for the academic marketplace as well as other marketplaces!
UPDATE: I found the 2007 rankings for the world's best universities. See also 2007 rankings for the best in the US.