The home and search results pages of YouTube’s mobile site will now serve up advertising, announced the YouTub Biz Blog. With a traffic increase of 160 percent in 2009, YouTube decided it was the right time to expand advertising opportunities from its Web site to its mobile site as well. Mazda was one of the first advertisers to jump on board. The ads are full-day banners, introduced after several months of testing. While it can be sold as a YouTube banner package, we’re not clear on whether a business can purchase mobile-only.