Futex and SysV Semaphores...

Does anyone know if the implementation of System V Semaphores uses
futexes under the hood on nptl based systems (i.e. RH 9)?  The second 
question is if this is the case, can I expect an incremented semaphore 
to be decremented when a process dies, or is that too much to expect (or 
perhaps would break things)?

thanks...james