Via Why Are We Back in Iraq?, on November 4 at a small rally in New York City, police showed up with dogs and machine guns. Then on November 9 two tanks showed up at an antiwar demo in Westwood, a district of Los Angeles near the UCLA campus. The video is at LA Indymedia.

According to the Washington Post, here's what they have planned for the inauguration—

As tens of thousands of people come to Washington to watch the Jan. 20 swearing in, the city will be filled with military personnel, FBI agents in full SWAT outfitting, snipers on rooftops and scores of bomb-detecting dogs. The region's air defenses have been strengthened to prevent intruder aircraft, and sensors will be deployed throughout the area to detect biological, chemical or radiological material.

About 2,000 out-of-town officers will help with security and traffic details. Undercover officers will work the crowds, and D.C. police officers will be posted every six to eight feet along the parade route.

Plans call for sturdier barriers and more checkpoints and metal detectors along the parade route than in previous years. Officials also are setting up a higher-security ticketing and credentialing system for some events, to prevent people from using counterfeit materials to get into the balls and more restricted areas.

The Post, as usual, portrays this as a response to 9/11—

Security is always tight on Inauguration Day, but it will be magnified for the first inauguration since the Sept. 11, 2001, terrorist attacks. Law enforcement officials have been preparing for months to protect U.S. and world leaders and citizens who attend.

But it is as much a response to security against antiwar protestors as it is to would-be terrorists, and here's the clue—

[O]fficials said the new Joint Forces Headquarters-National Capital Region is prepared to pre-deploy 4,000 active-duty combat forces in the District -- a significant departure from past inaugurations.

The military will support civilian authorities, if needed, and officials said they plan to project a much more forceful image than since at least the time of the Vietnam War.

About 2,000 troops, including members of the 82nd Airborne Division, were flown into Washington for Richard M. Nixon's inauguration in 1969, and some were stationed along the parade route. The military also helped protect the parade route for Nixon's second inauguration, in 1973. In recent decades, uniformed guards have played a mostly ceremonial role and specialized response teams stayed backstage. [emphasis added]