The Times discovered a mistakenly posted page at the Advertising Research Foundation — a group hosting a conference on audience measurement in New York Tuesday — that listed plans for Google to reveal the service at a 5 p.m. session. The page has since been taken down at Google’s request, but in a funny twist, can still be found via Google’s cache feature.

An inside source told the Times the new tool will use a variety of audience measurement data, search engine data, and third-party information to break down the demographics of various web sites and then help plan out the best strategies for ad agencies. It sounds like it’ll be geared more for big agencies than for individual sites or companies.

AdPlanner is expected to launch as a free service.

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