The DM client was not included in the game box. Obsidian stated that it would be available for download the day NWN2 was released , but that was brought into question by Feargus Urquhart's statements at a San Diego Comic-Con NWN2 presentation . He later clarified his statements by saying, "We are working on what we can and can't get done. My hope is that we can release as a Day 1 patch as much of the DM Client functionality as possible. [....] The important word in one of my previous sentences is the word 'hope'. We just don't know yet what we will be able to get done and not by the Day 1 patch." 
The DM Client, was, in fact, released, and is under ongoing development. A discussion of its current features, bugs, repairs and planned upgrades is here:
Obsidian previously stated that no features have been dropped from the NWN DM client, and it will include some enhancements. For example, entire parties can be jumped from one spot to another rather than one character at a time. Also, the DM's camera will be free roaming so that their avatar doesn't necessarily have to be in the immediate vicinity of other players. 
Obsidian Lead Designer, J.E. Sawyer, posted an update on the DM Client on 12th October 2006, he mentions that they are on schedule for the functionality that NWN1's DM Client had before it's 1.67 patch. He doesn't confirm a date for the release for the DMC as yet. 
Closely linked with the DM Client is the DMFI tools, which round out and make more complete the DM Client functionality.