You can use it to get standard results by adding "g" in front of your query, but this service should be used for queries that usually return an OneBox, like stock quotes, weather in a certain city, currency conversions, price of a product or local results. Google has recently added real-time flight info so you can just text the name of a US flight and find the time of the departure. Or text the name of a airlines company to find its phone number. The service is optimized for mobile phones, so there are shortcuts for common words like "weather".
Google SMS was launched in 2004:
SMS stands for Short Message Service, and Europe and Asia have thoroughly embraced this text messaging technology. Using your phone to send and receive text messages is a newer phenomenon in the U.S. Now we're getting into the fray with Google SMS. It's a way to access Google for precise information from your mobile phone or handheld device (like a BlackBerry).