* Simply take a fresh Ubuntu 8.04 install (which gets Apache 2.2.8), add "RLimitCPU 2 2" to the "default" Apache site file, drop the script above into the "cgi-bin" dir, and run the CGI. You'll see that the CGI process is *not* killed.
* Do the same thing on a Debian "stable" system (which gets Apache 2.2.9), and the CGI process *is* killed.
* Rig up a build of upstream Apache 2.2.8 (no Ubuntu patches) to use esssentially the same config file tree as a fresh Ubuntu 8.04 install (and running on the same Ubuntu 8.04 installed system), and the CGI process *is* killed.
At this point, unless I made a mistake while troubleshooting, the problem appears to be in Ubuntu-specific patches to Apache.