Good thing my mobile provider is Cingular, I guess:

The USA based mobile operator, Cingular Wireless has managed to get a patent on the concept of using emoticon on mobile phones. While the aim of the patent is to enable the displaying of MSN style graphics on handsets, they also managed to patent the delivery of text based emoticon - so presumably sending :) via an SMS - if selected via a dedicated or softkey, would be a breach of the patent in future.

Cingular Patents the Emoticon :(: Link via textually.org