"Finally, finally , the president has decided to confront the root problem in our troubled occupation of Iraq: the spin deficit."
It seems at first that the main point of the speech was PR. There are no policy changes, and he certainly wasn't addressing the Chalabi-Iranian agent issue, so there was no meat to the speech. It was simply an attempt to show the President being, well, Presidential; to show he is involved and cares what happens.
Yet the White House apparently only asked for air-time on CNN, FoxNews and one other channel, but none of the major networks (ABC, CBS, NBC, PBS). While cable is pretty ubiquitous at this point, the effect of pre-empting prime-time programming for a Presidential address is a bit of show that gets attention. If you are shooting for PR, this is the attention you want. However, if you want to make an empty gesture because you know you have nothing substantial to add, then this would be one way to do it.
Similar to having a press conference and picking only those journalists who you know will toss you softballs.
There is nothing wrong for drumming up some good press for your policies, its when you refuse to answer tough questions publicly and toss of carefully constructed non-speeches that you begin to look calculating. If these speeches are as important as the White House would have us believe, then they would have put it on the networks.
There will be four more of these speeches in the coming weeks. We'll have to see if the President is willing to make some major policy announcements in these speeches, or if he will stay with the non-speech speech.