Just in case you’re interested, this Time cover story on him from a couple of years back actually does a reasonably good job on the broad strokes: http://www.time.com/time/magazine/article/0,9171,2048299,00.... as does this NY Times one: http://www.nytimes.com/2010/06/13/business/13sing.html - there's also this intro by Peter Norvig to a Google Talks event with Ray from a month ago: https://www.youtube.com/watch?v=zihTWh5i2C4
The basic idea is that exponential growth in tech will result in strong AI, advanced nanotech, biotech, and neural interfaces that will lead to a near utopian civilization (if things go smoothly) in less than forty years. As outlandish as it seems, he actually makes a fairly convincing, well-researched case, and has had a pretty impressive career as an inventor and tech prognosticator. Needless to say, he’s a very polarizing figure.