I don't think Dennis' run is necessarily a waste even though he isn't going to win. He actually did better against Pelosi than most Republican candidates have done, and it will help the liberty movement in San Francisco's Republican Party. It could also help Ron Paul win that district in the 2012 primary. Last time out he actually won the endorsement of the San Francisco Examiner. That's the city's leading newspaper and such papers rarely endorse a candidate with no chance of winning. He also won the endorsement of Cindy Sheehan a Democrat who founded the anti-Iraq War movement and who ran against Pelosi as an independent in 08.
Without any party affiliation on the ballot and having gained name recognition, Dennis should be able to do better this time out. If he does exceptionally well, then his support will be sought by future statewide GOP candidates. Such support would come with a price tag.