Bill Slawski has recently reported on a Google patent to deliver ads on your cell phone. After reading the patent, I happened to be playing with Google SMS yesterday and received my very own (obviously reduced) ad that read:

(Ad)Hotels.com
Great Hotel Rates!
Hotels.com
800-449-4167

Here is what Adwords has to say (my italics and bold for emphasis):

In some cases, the local business ads may also appear with relevant searches on Google Maps for mobile. Ads appearing with mobile search results may contain only two lines of text, so local business ads may show in a shortened form on mobile searches. Currently, advertisers aren’t charged for impressions or clicks accrued by local business ads on mobile searches.

The text versions of your local business ads may also appear on Google SMS queries. Due to the limited amount of space in the SMS format, your ad text may not be included in its entirety. However, your business name and contact information will be included.