LPC: Booting Linux in five seconds

Agreed, I understand the desire to do 'booting in 5s' without cheating, but CUPS is probably one exception here where cheating is okay:
1) it's unlikely to take much CPU or IO load (if it does then it's a bug) so starting it in the background won't be felt as a slowdown for the user.

2) users are unlikely to print just after starting the computer so launching the desktop before CUPS is okay.

3) the critical part for the user here is the 'time to print' if having to find a network printer really slow downs printing then it make sense to have CUPS running all the time, not on demand.