Nice article about pull-based advertising. Last time I posted something about this, I received a snotty email from a guy at TxtVrt (www dot txtvert dot co dot uk, no google juice from me) insinuating that we'd nicked the idea from them. More realistically it's such a blindingly obvious thing to do that I can't see why this isn't already endemic in the UK.
It's such a cheap and easy thing for an advertiser to do, to track effectiveness and provide a return-path. Can anyone reading this see a downside to it, particularly at a time when web URLs are usually stuck at the foot of a billboard?