I am not sure yet if President Bush is seriously planning to conduct his own enquiry into Katrina, or if this was just a poor choice of words.
If he does end up holding an enquiry into the events, I predict this will be his undoing. It is always the cover-up that creates the political scandal. Some evidence will come to light during this enquiry which will be uncomfortable for the administration, and it will not be properly reported. And that will, in time, be the scandal that finishes him.