variable expansion in .forward?

Is it possible to get ${local_part} to be expanded inside pipe commands
in a users .forward file?

I've tried a few combinations and it always ends up as null.    
--
Lee McLoughlin.                         Phone: +44 171 594 8388
IC-Parc, Imperial College,              Fax:   +44 171 594 8449
South Kensington, London. SW7 2BZ. UK.  Email: L.McLoughlin@???