How many people are in the US army in 2010?

Slightly less 3 million spread between active and reserves.

The US military hires less than 0.9% of the population but accounts for 23% of our federal spending.

This number represents the entire United States fighting force to include but not limited to Marine Corp., Airforce, National Guard, and possible NSA, Homeland Security.

The Army alone consists for approximately 700-750,000 soldiers at any given time including active and reserve components. According to the Armed services page in wikipedia, in 2009 there were 548,000 active and 200,00 reserve.