Not sure why this question just posted to the forum when it looks like it was written in Sept. However, it did pop up on my notification after it posted to this forum, so I will respond, but please forgive the amount of time that appears to have passed since this was originally written.
As epstein noted, you should read your contract carefully; however, her assertion on "at will" employees is most likely incorrect when it comes to contract law (but obviously, this could vary from state to state). You should not be taking legal advice from epstein, or myself for that matter, because neither of us should be giving legal advice when we are not licensed by any state to do so. But from my understanding of contract law, having a contract is very different from being an "at will" employee in any state.
An article on FindLaw.com reads:
In most states, employment is generally considered "at will," meaning that the employer can terminate employment (or the employee may voluntarily leave) at any time. An employer's right to fire an employee may be limited, however, where the employee can show that the employer entered into either an explicit contract to retain the employee for a certain length of time, or an "implied contract" which dictates that employment will be terminated only for specific disciplinary reasons.
You can see the entire article at
http://employment.findlaw.com/employment/employment-employee-hiring/employment-employee-hiring-contract.html
Unfortunately, the best thing is to probably let it go. If you do want to take action, you must remember that the way travel contracts are framed, you are not entering into a contract with the hospital, you are entering into a contract with your travel company. This is an important distiction because your cause of action would not be against the hospital, it would be against your travel company. Whether or not you want to go down that road would be up to you.
If you do want to go forward, you will need to see in which state the items in your contract are governed. You would then need an attorney that was well versed in the application of contract law in that state.
It's never a good situation when a contract gets cancelled. However, I have had a contract cancelled that cost me a good bit of money because I had already begun work at the contracted hospital (and traveled 2000 miles to get there, and set up my cable, phone, Internet, etc). At least you saved yourself from having to travel to the location and turn right back around. Again, I know it sucks to have this happen, but trust me, it could have been much worse.
Consider looking into another travel company unless you have history with this one. Many companies know repeat offenders of this type of behavior and can steer you clear of such assignments.
Sorry that this happened to you. I hope the information helps.
David
http://travelnursesbible.com 
