How are operators of small UAS craft supposed to know about flight restrictions? The FAA is requiring all operators of small unmanned aircraft systems between 0.55 and 55 pounds to register. This is to help ensure that operators of model aircraft and drones act in a responsible manner, etc.

In the Registration and Marking Requirements for Small Unmanned Aircraft document available from the FAA (PDF), there are examples given of drones being flown near wildfires that interrupted firefighting efforts, despite a temporary flight restriction for the area surrounding the fire.

It seems obvious to me that operating an RC aircraft near a wildfire might not be a good idea. However, "temporary flight restrictions" could exist in other cases that aren't quite so obvious. There is no requirement (as far as I know) for sUAS operators to check NOTAMs, aviation charts, etc.

How can an operator be sure they are in compliance in every situation? It seems like it might be very easy to violate some regulation inadvertently.
Information about current and future TFR areas is available from the FAA, even as an easy-to-read map. If someone is planning on flying a manned or unmanned aircraft, that should be on their list of things to check ahead of time.

As far as other airspace restrictions, we have a question detailing the different types of airspace. It would be worthwhile for a UAS operator to learn enough about reading charts to at least know the airspace in the area where they intend to fly.

Another option would be to attend ground school or at least do some amount of self-study. Just as pilots need to know how to operate according to the rules of the airspace system, UAS operators could benefit from the education.