This is the kind of thing I have been hoping for for years. The real test of its usefulness is the databases that the listings are pulled from. I'm not sure where Google is getting this data, but I would love to know. They certainly could afford to pay for API access to virtually all MLS systems but I think many will not allow it.
Another issue for agents is, what control do you as an agent have over what info is in that listing. If you can control what shows there keep this in mind: this information should be to help people determine if this home meets their search criteria, not to create a lead for you. If this takes off Google will be much more efficient at helping them find a list of homes than you ever will. Your job is to handle what Google can't, which is guiding them through the home sale/purchase process.