in ActiveChat, this was one of the best variables. For example, a contact messages "i need help with signing up". That is assigned to the variable "contact.last.sms" or "contact.last.email" This allows us to create a notifcation text to our client in the triggers saying "you have a new text message from contact.name and they said contact.last.sms"
then when the contact sends another message, it is updated automatically to the new message.
this can also be done to send attachments with audio recordings and voicemails!