Useful Information, Brilliant Marketing
Apple provides a thorough catalog of all the CSS bugs in Microsoft Internet Explorer, with a succinct guide for working around them,
This (like the Switch campaign) is extremely clever hardball. It's a well written, informative, and factual article, embedded in the developer's technical library; it doesn't look or feel like marketing. It's just trying to help. It's got no axe to grind. And it just happens to position the competition in a negative light, and lets the silver-and-white computer people lend you a hand.