Archer, D., Aijmer, K., and Wichmann, A. (2012). Pragmatics: An Advanced Resource Book for Students. London and New York: Routledge would be a recent and a good source of info
Stephens, G., & Matthews, D. (in press). The communicative infant from 0-18 months: The social-cognitive foundations of pragmatic development. In D. Matthews (Ed.), Pragmatic Development in First Language Acquisition. Amsterdam: John Benjamins.
You might be interested in looking at a functional approach to language also. The seminal work would be VERBAL BEHAVIOR by Skinner (1957). Updated applications would be Verbal Behavior - Milestone Assessment Placement Program (VB-MAPP; Sundberg) and Assessment of Basic Language and Learning - Revised (ABLLS-R; Partington). A recent review of this approach was published by Plavnick and Normand (2013: Journal of Applied Behavior Analysis)
You might want to look into the work done in early identification of autism spectrum disorders. Researchers such as Peter Mundy, Connie Kasari, Catherine Lord, and Marie Eigsti have examined early signs of atypical social attention and language (both verbal and non verbal) development.