I continue to be fascinated by the ways in which computers (and new technologies in general) change the terrain in so many (all?) fields. Dylan Loeb McClain's chess column in the March 5, 2011 New York Times, titled "Still No. 1 in the World, by the Thinnest of Margins", comments on the fact that the world's three top-ranked players are only separated by a range of 9 points (out of 2,800 points). Garry Kasparov, the top-ranked player for 20 years until he retired in 2005, was, McClain notes, was often 30 or 40 ratings points ahead of his closest rival.
What I find of interest is that McClain attributes this to the fact that players today have access to the same databases of games (want to review the Immortal Game? you can find it in any number of places, and step through each amazing move. What about a match between Salo Flohr and Max Euwe, 1932? Yep. Or all of Bobby Fischer's games, or ... see chessgames.com, or chess.com). Plus they have access to powerful computer chess engines to experiment with. And for the average punter, online play can dramatically expand one's board experience. So the tools of preparation are more evenly available: "Today, players have access to the same databases and computers when they train, and native ability is more important than ever" (which is another interesting insight).
Also see this post re: an article by Kasparov on computers and chess.