The popular third-party instant messaging platform Meebo has announced that it is making its ad offerings available across a network of 40 publishing partners, including Sugar Publishing, StarPulse and Current TV. Combined, the sites in the network will provide access to 45 million unique visitors per month.

Meebo intends to create a communications and social network oriented group of sites that can compete with MySpace and Facebook in providing brand advertisers, in particular, with the scale they need. To that end, Meebo has created a non-standard, ad unit that it claims gives more bang for an advertiser’s buck, with a 1% CTR and 10% of engaged users then forwarding the ad to their friends.

As the most successful social and mobile networks expand exponentially, we are going to see smaller sites and networks collaborating more and more in order to compete. The recent Facebook feeding frenzy shows just what kind of opportunities may lie ahead for imaginative advertisers as these new high-volume platforms emerge.