If systems admin is your flavour of Frutopia, then take a look at "Perl for System Administration" from O'Reilly Press (the sea otter book :). It was just published in July 2000, but I wish I had it earlier.

It contains oodles of very handy sample scripts for topics like log monitoring, network monitoring, database management, LDAP directory services and other handy sysadmin stuff.

But if you're looking for a general language reference, then the Camel Book (Programming Perl) is probably your best choice. I wish it were a bit more in-depth on some topics (like IPC), but then it would wind up really really huge. In any case, my well-thumbed, sticky-note-annotated copy never leaves my arm's-reach at work -- it's really worth your money.