Hi!
I'm not sure if this is ASB due to the increased security, but consider this.
A terrorist group such as al-Qaida decides to attempt a terrorist attack in Washington during the inauguration. The group claims (realistically) that Obama is impregnable given the Secret Service, no fly zone, and so forth. However, it knows that 2 million people are going to be converging on Washington for the inauguration. It decides to go after the civilians (for instance, doing something to the overcrowded Metro or roads). The Mall itself is probably too well protected to do anything.
Three scenarios.
1. The attempt is foiled during the inauguration.
2. The attempt succeeds and 100 people are killed in Washington.
3. The attempt succeeds and the group uses a biological weapon in the Metro whose effects are not noticed until the visitors have gone home -- perfect vectors for the weapon.
ACG