Kieran -on behalf on the Drupal Association- started an experiment with Google ads on Drupal.org. Currently it is only on the paid-services and hosting pages.
Personally I would be fine with running skypscraper format on all forum pages but this is just a temporary test to see how the Association can make some much money without giving the community the feeling that Drupal.org will become a linkfarm. There are lots of less irrelevant ads now, about Typo3 and Joomla related services for example so if you are a Drupal service provider, you might want to sign up at Google and run a dedicated ad on drupal.org. A good way to gain some attention and helping the Drupal community as well.
While we are on the subject of money and advertising, the Drupal Association had some positive news, a Google Summer of Code cheque, the price money from the Packt CMS award and a small profit from the DrupalCon in Barcelona. This money will be spend -amongst others- on hardware and covering maintenance costs of running Drupal.org.
BTW: if you are in to "Advertising 2.0", be sure to read IBM's statement on how the advertising will change the couple of years.