Doctor Who Magazine #419 has released the titles of Doctor Who series 5 episodes four, five and six
5.4 The Time of Angels
5.5 Flesh and Stone
5.6 Vampires in Venice
It's pretty clear episodes 4 and 5 will be the two-parter that will see the return of the Weeping Angels and Professor River Song.
Thanks to Denyalle for the heads up!