I usually avoid conspiracy theories like the plague. I do not purport to be an expert on anything. But, I've run into this theory a couple of times on the web, most recently on The Western Confucian. A couple of things have recently diverged to make some worry about the future direction our country could be taking.
First, the U.S. Army, as of October 1, has deployed 3-4,000 troops on U.S. soil whose mission is crowd control using both lethal and non-lethal methods.
Second, up until recently, it was illegal for U.S. troops to patrol on U.S. soil. On October 17, 2006, George Bush signed the John Warner National Defense Authorization Act allowing the president to employ U.S. troops to restore order in any state in the United States. Although repealed in 2008, President Bush attached a signing statement saying that the Executive branch did not feel bound by those changes.
Third, during the recent debate about the federal bank bailout bill, congressman Brad Sherman said that members of the house were threatened with martial law if they didn't sign the bailout bill. Alternet.org points out that the Army's First Brigade, now deployed and practicing its crowd control techniques on U.S. soil, potentially puts some real teeth into this threat.
Below is a video of Congressman Sherman's statement.