I had high hopes that OS X 10.4 would ship with a higher default maxproc. My old post on this subject still worked for 10.4, but what a pain that is, and you have to redo it after some System Update operations.
I just finished reading an article on launchd over at AFP548, and he mentions launchdctl for controlling launchd. One thing this
utility allows you to do is set the resource limits for things that launchd launches. And one of the things that launchd starts is the WindowServer!
So, you just need to have launchd launch processes with a higher limit. If you run launchctl limit right now, you will see that the maxproc is set to 100. To change this, you need to create the /etc/launchd.conf file (if it does not already exist) and add the following line:
limit maxproc 512 2048
The first number is the soft limit and the second number is the hard limit. You can pick different values if you want.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20050709233920660