My thoughts on why Google is doing this.

[Godwin Merac]

I guess Google is using us to field test their voice recognition
software. It's pretty smart of them to utilize their heavy web
presence to get just everyone to babble into there recognition engine.
Now they can see how well it's actually working under real-life
conditions (all kinds of different dialects from all over the
country). And it doesn't cost them a dime.

As for why do they need it. Here is a clue. Following quote was taken
from http://www.google.com/press/highlights.html:

"Partnering with BMW to provide voice-activated access to Google in
upcoming Internet-ready automobiles. Search terms can be spoken into
the car's speakerphone, and search results are quickly presented on a
built-in LCD screen, or on a user's Internet-ready mobile phone."

Google rocks,
Godwin.

[Quicksilver]

I agree, that was an sxcellent observation.