Nice article over at AgAge.com by David Armano about the microsites and some of the predictions that the vehicle is dead.
http://adage.com/digitalnext/article?article_id=130373
David basically, and very intelligently, makes the argument that most marketers and their agencies simply got lazy. Microsites became another one of those "build it and they will come" vehicles, and not enough time was being spent on actually determining what would be an engaging experience for the user.
"And so the formula had begun. Launch a campaign, build a microsite, buy online media to drive traffic to it. Everything was in its place -- advertisers now had a presence on the web, clients were happy about it, and the big money was still being pumped into the traditional channels because that's how it's always been done. In the past year lots of us have had a grand ol' time proclaiming the death of the microsite, and with some validity. Fact is, the internet is littered with thousands of them and the majority are either promotional in nature, designed to win awards vs. serving up value, or simply provide no incentive to ever return to them. On top of that, most of the microsites I come across are difficult to use, take way too much time to load, crash my browser or use contrived marketing language written by professionals who have spent years perfecting their craft."
Microsites can still be an effective weapon in a brands marketing arsenal. But as always, you need to insure that the experience will be highly engaging and entertaining, and also provides the user with an experience that motivates some sort of relationship with the brand.