ExactTarget Buys CoTweet, Sets UP “Social Media Lab”

Email marketing software giant ExactTarget has agreed to acquire CoTweet, a young company that offers a tool that enables multiple people to communicate on Twitter through corporate accounts.

CoTweet will continue to operate from San Francisco as a business unit of ExactTarget, essentially taking charge of the company’s social media product development. CoTweet co-founder and CEO Jesse Engle will lead the San Francisco operation and head ExactTarget’s new “social media lab”.

Terms of the agreement have not been disclosed, but we’re digging.

CoTweet was founded in 2008 and offers a browser-based collaboration platform that allows companies to manage multiple Twitter accounts from a single dashboard, support multiple editors, track conversations, assign roles and create follow-up tasks. Its high-profile customers include Whole Foods, McDonald’s, Microsoft, Ford, Dell and Pepsi, among others.

The company raised just over $1 million in seed capital from Ron Conway’s SV Angel fund, The Founders Fund, Baseline Ventures, First Round Capital, Maples Investments and Freestyle Capital.

Twitter COO Dick Costolo also managed to squeeze in a quote in the official press release, saying that he sees the acquisition as a “strong validation that valuable, sustainable businesses are emerging from the Twitter ecosystem”.

ExactTarget claims annual contracted revenue of around $114 million for 2009, a year in which it raised a staggering $145 million in venture capital. The company employs more than 600 people, recently opened an office in London and counts Nike, Best Buy and UMG among its clients. You can read the company’s letter to its customers here.