Businesses offer all sorts of services they don't make money on.
"Loss leaders" are well-known (supermarkets supposedly sell milk, eggs, etc.
below cost to get people in the door, and make up the difference on
high-margin sales wine, beer, cigarettes, meat, or whatever).
High-tech businesses offer unprofitable services in order to get
profitable business through interoperability, goodwill, the
network effect, etc. I've worked for a couple
of companies that supported Macintosh or OS/2 simply because the competition
didn't, getting Brownie points (or allowing interoperability, or whatever)
with the customers' Mac or OS/2 users even though they lost money on every sale.
Google might be applying similar logic here...
Finally, note that Google limits SOAP queries to 1000/day/customer, limiting the cost, and
getting their name/email, which presumably has some value even if they don't
sell it or send spam.
