I am required to arrive at my work at the same time each day. My boss has said multiple times that we're not to be paid until we "leave for a job," which isn't usually for 30 minutes to an hour after I arrive. I spend that time doing other job-related stuff, and sometimes I sit and wait.

My boss specifically instructed me that I am not to be paid for time waiting. Same for time spent at work after I have arrived back at our building.

Understand, I am required to do certain tasks before leaving and after arriving back at work. Also, I must sit and wait for my coworkers or wait for other reasons before leaving in the morning. (I'm not delaying my departure.)

According to this page:
http://labor-employment-law.lawyers.com/Pay-for-On-Call-Time.html
...My boss is violating the law, specifically the FLSA.

On average, I'd estimate following such rules would result in me losing 1/2 to 1 hour each day. This is time spent at work, either waiting or working, but required to be at the building.

Is this legal?

The main thing I'd like to know, if this is illegal, is what law or regulations my boss is breaking.

Assuming that you are non-exempt, if you are required to be there, you are required to be paid for the time.

Thanks for the super-fast reply!

I am paid hourly, and am not salaried. I believe that makes me non-exempt.

If I may ask, what laws or regulations is my boss breaking?

The Fair Labor Standards Act, which states that you must be paid for all hours worked.

Time that you are required to be there is considered time worked.

Patty or DAW can give you the specifics and the definitions. Where payroll issues are concerned, I deal only in the broad strokes. They're better with the fine points. ;)

Several ways of looking at this. The first webpointer is to a federal DOL factsheet on hours worked.
http://www.dol.gov/esa/whd/regs/compliance/whdfs22.pdf

If you want something a bit more authorititive, that would be regulations. I have cited one pretty close to your situation, although if you try moving around that website, you will see a number of regulations that somewhat effect your situation. (The factsheet is generally easier to follow).
http://www.dol.gov/dol/allcfr/ESA/Title_29/Part_785/29CFR785.14.htm