PowerBook won't sleep, where to start?

[Sean Schertell <debianppc@datafly.net>]

I apt-get installed pmud, and it started.  But when I type sleep or close the 
lid, it just keeps running -- same after restart.

TiBook 550
Debian PPC (from sarge beta4 installer)
KDE 3.2.2

How should I troubleshoot this?  Is there a kernel module I'm missing?