Blog search and tracking company Technorati has purchased AdEngage, an online ad network that reportedly serves over 12 billion ads across 4,000 websites per month.

AdEngage's platform to lay groundwork for self-service ad network, Technorati Engage, which targets blogs and social media sites. Engage went live in private alpha yesterday.

The goal of Engage is to "help bloggers at all levels make money, while at the same time creating an effective and safe vehicle for brand advertisers," according to the Technorati blog. The alpha launch offers Technorati users access to AdEngage's existing text and PhoText products. When it launches in beta next month, 125×125 square ad space will be added, followed by full display capabilities and an array of "popular [Internet Advertising Bureau] display ad sizes" in 1Q09.

Publishers interested in joining the Engage Exchange will be evaluated on for compliance with Technorati's quality standards.

The Technorati Media network went live in 2008 and includes over 40 million unique users across 45 blogs and social media sites.