It means that our government is responsible for what happened on 9/11. Sure, someone else was flying the planes, but our government allowed people to carry weapons onboard an aircraft and hijack them.
Our government allowed those people to enter our country.
Our government gave money to the Taliban which they used for terrorist purposes.
Our government pissed off the terrorists, their countries and their organizations.

And now, 2 years later, our government has done nothing but get more Americans killed while trying to find the 'person' responsible.

No one person is responsible for terrorism. Capturing Bin Laden or Hussein will do nothing but give terrorists more reasons to hate us. The cycle will continue until we realize we need to get the fuck out of everyone elses problems and deal with our own. Close our borders to everyone. Send every illegal back home. Manufacture everything we need in our country. Ignore the rest of the planet.
We could fix this whole place up in 10 years.