CiviCRM Integration wtih WhatsApp
They haven't been any to my knowledge, but assuming whatsapp as an api to post messages, it shouldn't be too complicated to implement.

If you are interested, you could write an extension and use the searchtask hook to add a "send via whatsapp" action
http://wiki.civicrm.org/confluence/display/CRMDOC/hook_civicrm_searchTasks