And maybe they are using Google´s API. The only problem with that is the limited number of requests (1,000 automated queries per day).
That´s legal, and even promoted by Google.
http://www.google.com/apis/
With the Google Web APIs service, software developers can query more than 3 billion web documents directly from their own computer programs. Google uses the SOAP and WSDL standards so a developer can program in his or her favorite environment - such as Java, Perl, or Visual Studio .NET.