not quite as simple an answer as carl suggests. as with most legal issues, the answer here (in my estimation, and based on the information that you provided) is "it depends." check with your real estate lawyer, as he or she will be able to give you a more definitive answer
if the property is owned in a trust (as in carl's scenario) the trustee signs the deed.
if the estate is in probate and is an "independent administration," the administrator/executor signs the deed.
if the probate is a "supervised" administration, the administrator/executor signs the deed, but needs a court order to sell
if there is no probate of the estate, all the heirs should sign the deed.