Ye Xu, one of our CRM PMs in China, has developed an SMS (aka text message) add in for CRM 3.0. You can download the add in and the source code from CodePlex. The add in does more than just simple notifications. You can send messages, create/update records, query CRM etc. If SMS is an important part of your customer communications (or heavily used by your internal mobile users) then it's worth checking out this add in.