I am guessing that you will see no real-time TV reports from the Tiananmen Square area today, and little or no photography. This is based on personal experience there last night, China time, which also leads to personal advice for anyone in Beijing thinking of going there today.
During my time in Beijing over the past year and a half, I've often seen the square itself totally closed off to visitors, as it is at the moment. There are always plenty of security forces around -- soldiers in green uniforms, various kinds of police in blue uniforms, and "plainclothes" forces who are pretty easy to pick out, like strapping young men in buzz cuts all wearing similar-looking "leisure" clothes. But I have not seen before anything like the situation at the moment.
There are more representatives in all categories -- soldiers, police, obvious plainclothesmen -- than I recall seeing even during the Tibet violence in early 2008 or through the Olympic games. Also many people whom you would normally classify as fruit vendors, tourists from the Chinese provinces, youngish white collar workers male and female, and skateboarder-looking characters wearing cargo shorts and with fauxhawk haircuts, were last night walking up and down the sidewalks with their eyes constantly on visitors and drifting up next to people who were holding conversations.