Hulu's Senior VP of content Andy Forssell is on stage right now at a panel called Argue the Future 2: Return of the Future (hosted by our own Joshua Topolsky), and he indicated that Hulu had started reducing the number of ads the service showed to consumers in January based on feedback from users. Furthermore, Hulu intends to keep pulling back a bit more as it tries to find the right balance between sales and a positive consumer experience. Of course, Hulu somewhat controversially serves ads even to customers of the paid Hulu Plus service, and Forssell did admit that ads were starting to increase because its sales team was able to sell so many. However, it sounds like the company will work to strike a more balanced approach — but it doesn't sound like those ads are going away any time soon.
Update: A Hulu spokesperson let us know that there are a variety of factors in the quantity of ads, and that they typically will move up and down based on sales inventory — so a decline in January isn't necessarily a strategy change. However, Forrsell told us directly that the company does intend to gradually reduce the number of ads served to Hulu Plus users over the coming months.