On iMediaconnection there's an overview of the rich media state of the art. It touches some of the controversial points of this kind of ads (what about narrowband users?) and evaluates the importance of interactivity in online advertising, as well as the secrets behind a successful rich media campaign.
Rich media ads represents only 17 percent of all online ads, but experts say the adoption isn't slow and the recent guidelines released by the IAB will surely help this segment to grow.