There are many similarities between Iraq and Vietnam in terms of the facts on the ground and a growing discontent with each war as well as the disconnect of the Presidents.
Both Presidents were Texans (Bush and LBJ) and both became increasingly disconnected from the reality of the conflict (Bush in general to any realistic facts and LBJ only made appearances on military bases given the loud and strident opposition to Vietnam).
Katrina now poses the same danger to the war on Iraq that the War on Poverty posed to Vietnam. The financial and physical commitment to rebuild after Katrina mirrors the ambitious War on Poverty by LBJ. However, LBJ ultimately had to abandon the war on Poverty at its intended level to commit to Vietnam.
President Bush is now faced with a similar choice in regards to Iraq and Katrina. He will also have to choose.