From the Air Traffic Control Handbook:

2-1-8. MINIMUM FUEL
If an aircraft declares a state of "minimum fuel," inform any facility to whom control jurisdiction is transferred of the minimum fuel problem and be alert for any occurrence which might delay the aircraft en route.
NOTE-
Use of the term "minimum fuel" indicates recognition by a pilot that his/her fuel supply has reached a state where, upon reaching destination, he/she cannot accept any undue delay. This is not an emergency situation but merely an advisory that indicates an emergency situation is possible should any undue delay occur. A minimum fuel advisory does not imply a need for traffic priority. Common sense and good judgment will determine the extent of assistance to be given in minimum fuel situations. If, at any time, the remaining usable fuel supply suggests the need for traffic priority to ensure a safe landing, the pilot should declare an emergency and report fuel remaining in minutes.

---------------------------------------------------------
We are trained, that when an aircraft declares minimum fuel, we are to advise the next sector if the aircraft is coming out of hold and is being handed off, and also management. Management will phone ahead and alert affected facilities. As a controller, I try and be accomodating, but like the above paragraph says, it's not an emergency. EFC's can change in a moment's notice, so I usually try and tell the holding aircraft what I think is going on, and an educated guess at how long it will be. Sometimes, we just don't know, especially when it's one facility shutting off another.