The current expected release date for the Microsoft Forefront Threat Management Gateway exam is July 23th 2010, although that might shift when it comes closer.
70-157: Exam MCTS
MCTS: Forefront Integrated Security, Configuring
July 23th 2010
Regarding a TMG MCITP cert, there is no information about that at the moment.
Edit: 29 July 2010.
Yesterday I found somewhere else that the official dates should be around the end of October.
TS: Microsoft Forefront Network Security, Configuring
premeditated Release-Date: October 20, 2010
TS: Microsoft Forefront Identity & Access Management, Configuring
premeditated Release-Date: October 22, 2010
TS: Microsoft Forefront Secure Messaging and Collaboration, Configuring
premeditated Release-Date: October 29, 2010
Edit: 21 October 2010.