Hey,
I'm running latest commit of 1.0-stable (6e92e9a55bf4eea29fe1cf4c3e513e92191a60a2) on debian with passenger:
apache2 => 2.2.16-6+squeeze7
libapache2-mod-passenger => 2.2.11debian-2

The box is a debian squeeze with 3vCPU and was 2GB memory.
I get a strange behaviour today with foreman/passenger taking all memory and getting OOM.
I restarted apache and get back to normal memory consumption. Then a few minutes later I had Kernel Panic
due to lack of memory.

I have ~150 hosts and nagios using Foreman API for monitoring.
I tried to tweak my passenger configuration with SAm :
I have now :

1. Passenger Configuration
   PassengerHighPerformance on
   PassengerMaxPoolSize 40
   PassengerPoolIdleTime 1800
   PassengerMaxRequests 400
   PassengerUseGlobalQueue on
   PassengerStatThrottleRate 120

And

<IfModule mpm_worker_module>
StartServers 2
MinSpareThreads 25
MaxSpareThreads 75
ThreadLimit 64
ThreadsPerChild 25
MaxClients 150
#MaxRequestsPerChild 0
MaxRequestsPerChild 200
</IfModule>

The memory consumption is always growing and apache restart make it low again