Hey, I just downloaded WhatsApp Messenger on my Android. It is a Smartphone Messenger which replaces SMS. This app even lets me send pictures, video and other multi-media! WhatsApp Messenger is available for Android, iPhone, Nokia and BlackBerry and there is no PIN or username to remember - it works just like SMS and uses your internet data plan. Get it now from http://www.whatsapp.com/download/ and say good-bye to SMS.
In short, I can now SMS friends and family with smart phones (regardless whether they are Android based, Apple, or Blackberry) for free.