I have been using Google 411 for quite a while now and I've been wondering if the 10 second ad they play is enough to pay for the service.   Well, I found out today why Google really made Google 411 – they want to collect the data for speech recognition software for video search!  Now that's a really creative plan.  Give away 411 services that people want in exchange for their voice and they never even realize they've given anything away!  

In an interview with IDG, Marissa Mayer said:

You may have heard about our [directory assistance] 1-800-GOOG-411 service. Whether or not free-411 is a profitable business unto itself is yet to be seen. I myself am somewhat skeptical. The reason we really did it is because we need to build a great speech-to-text model … that we can use for all kinds of different things, including video search.

By the way, 1-800-GOOG-411 works great – I use it all the time – except for "Berthoud," the town I live in.  I've even tried mispronouncing it (people tend to say it "ber-houd" instead "ber-thud") and it just doesn't get it.  So 1-800-GOOG-411 as long as you're not trying to look up my number … or the number of the best Mexican place in Colorado.