I'm with you, Dixie- I've worked staff and travel jobs all over the country, including MA, and no nurse there is making $56 an hour. That is likely the bill rate the agency charges the facility for her.
CapeCodMermaid- The agency gets $56 an hour, out of which they they pay for the nurse's salary, benefits, housing, and their own costs. The nurse is probably getting $24 - $30 an hour, plus having her housing provided. If that nurse has a home she pays for then she should have housing provided- I wouldn't want to pay rent or mortgage twice!

If she does not have a home that she pays for then the housing money is taxed as income.
If staff RNs add the cost of their benefits (usually about 1/3 of your salary I believe) to their salary, then add the necessary cost of the middle man (agency) the totals are pretty much the same.
Nursing News