Are social networking sites the next vehicle for advertisers?

MySpace, Facebook and other social-networking sites are all the rage, but they’re having to hustle to get advertisers on board.
These sites, which let users create home pages, blog and message friends online, are attractive to advertisers because of their rapid growth and young audience. The leaders, MySpace and Facebook, attract more than 5 million new users a month. (MySpace is owned by News Corp., which also owns The Post.)

But advertisers and analysts also question whether social networks can move beyond the hype and into mainstream marketing. The trick seems to be coming up with less formal and invasive forms of advertising that will appeal to young, tech-savvy users.