MARK AUSTIN THOMAS: You know Nielsen ratings, they keep track of what Americans watch on TV. Well, brace yourself. Nielsens are coming soon to an iPod near you. Marketplace's Lisa Napoli has details.

LISA NAPOLI: If you're watching TV on your cell phone or iPod, Nielsen Media Research wants to keep watch over you.

This summer, new meters will be tested that gauge the audience for non-TV TV viewing. Nielsen's calling it Anytime, Anywhere Media Measurement.

John Consoli of MediaWeek says it's an acknowledgement that TV is moving off the big screen to the handheld one.

JOHN CONSOLI: In the past year, more and more of the TV networks have done deals whether it be Apple for iPods or putting more of their shows on their own Web sites.

Nielsen hopes to roll out the mobile measurement service on a wider scale by next year.

In Los Angeles, I'm Lisa Napoli for Marketplace.