Even if this were a college student prank, believe that the bad guys are watching the response. The minimal media response and public concern over the Oklahoma bomb (student blows self up) are notable. In our race not to offend people, it seems that Islamic extremist involvement is immediately discounted without a seemingly thorough investigation. The officials do not want to panic the public. I remain concerned that the terrorists are using these responses and American political correctness to plan their next attack.
Look for a mall or maybe a University. However, upsetting the university student environment will not achieve the desired terrorist effect. Right now, the vast majority of higher education students and faculty are anti-war and liberal. Attacking them might change their views. A mall, on the other hand, would strike at the heart of capitalism (assuming that Wall Street is too hard of a target currently, that is, until such time as the terrorists have a viable bio or chem weapon).
Watch these events closely, and regardless of who is responsible, the terrorists are watching our response. If we randomly implement a variety of security measures, it will extend the planning timeline and just maybe, we will be successful overseas in removing funding, eliminating active terrorist participants (willing suicide bombers with the requisite knowledge of English), and interrupting their leadership to keep the terrorist organizations in disarray. The long-term goal is to change the opinions of the generation of people who think that what the terrorists are doing is OK.
Best regards to all.