Another contextual banner ad network?

Online advertisers in the USA are being spoilt for choice - there is now yet another entrant to the contextual banner ad market. ContextWeb has released the technology, though it’s still unknown how much of a threat they’ll represent for the main players. In my opinion, whoever is the first to bring out a rich media offering (ie, Flash) plus a very large distribution network still has a massive opportunity. An aggregator of systems perhaps? Unlikely to happen - but surely a Flash offering is only a few months (weeks??) away.