As I’ve noted before I think, it’s definitely a favourite sport of developers to rabidly support either the big evil corporate Microsoft, or the Luke Skywalker-esque rebellion led by Firefox, W3C, open source etc (though you have to wonder when Google will replace the former …)
One glaring example of Microsoft not obeying the W3C standards it professed to was the box model “bug” which lasted until the release of IE6. In a nutshell, IE presumed that padding on a content “box” should actually be included in the stated width, quoting the real world example of a cardboard box (ie. you wouldn’t quote the width of the cardboard separately if measuring a box, just as you wouldn’t include the cardboard in the weight).
This seems a reasonable argument although you can probably defeat with a lot of web examples, as padding and margins are more likely to follow the print world as an example. Maybe they should have ditched calling it a “box” to solve the argument … but in any case IE6 and IE7 have generally fallen into line on this behaviour.