Have you ever seen the google ad sense advertisements in the right column? They have been up since July 16th and have been clicked on by approximately 12 people, as I did actually click on five of them over the last months.
I think the idea of adjusting advertisment to content (aka readers’ and writers’ interests) is quite valuable.
On the other hand, if this service is used as sluggishly on other sites as it is here, then I very much doubt its economic viability… oh, and by the way, at the current clickrate I will only need to keep this site for another 49 and a half years to receive my first check from google ;).