The Nielsen Co. said it will start measuring the mobile industry after agreeing today to acquire Telephia, a San Francisco-based company that researches wireless consumer behavior.

Terms of the transaction, which is subject to regulatory approval and expected to close in the third quarter, were not disclosed. Telephia and Nielsen are both privately held companies.

Perhaps, Seattle-based M:Metrics, which also tracks trends in the wireless industry, was also a candidate?

After all, Will Hodgman, who co-founded M:Metrics in early 2004, has ties with Nielsen. He founded a company called AdRelevance, which was later purchased by Jupiter Media Metrix. It was through Jupiter that he came to work at NetRatings and the the Nielsen//NetRatings service.

M:Metrics is financially backed by investors including I-Hatch Ventures, Prism Venture Partners and Kantar Group.