Yes. See the linux-pmac HOWTO:
  ftp://cap.anu.edu.au/pub/linux-pmac/old/ppc-howto 

From the ppc-howto:

For netbooting, you will also need vmlinux.coff as well as:

- another machine (the "server") running some flavor of Unix
  (e.g. linux) which you can configure to run bootpd and tftpd
- an ethernet connection between the Mac and the server
- an IP address for the Mac on the same ethernet subnet as the server

jonh@cs.dartmouth.edu