It is not absolutely impossible to get a lender to agree to a short sale on a home who's owner is current and not in default. The odds are pretty low though!
If the homeowner is being transfered and has proof from an employer it may make it some what easier, however the same issues of proving there is no savings and it’s impossible to continue to make two house payments will still be required along with a financial statement.
If this owner is not being transfered and has no legitimite reason to move other than wanting to, the only choice may be a loan modification and renting the property for a few years upside down to get to a point where the property is worth more than the loan.
You did not give a lot of specific details but hopefullly you understand?