It's still needed. The Android process manager is actually very efficient for a pretty decent range of system sizes. You should look at tuning the /sys/module/lowmemorykiller/parameters/minfree variable (check out the thread at http://forum.xda-developers.com/showthread.php?t=622666 for some investigation), but certainly don't disable it.

Even on my Nexus one (which has ~400MB of usable RAM for userspace applications), Android is reliant on the memory killer.

Also note that you don't want a huge swap, unless the N900's NAND access is _really_ fast. It's often faster to suspend/resume processes in Android than page parts back into working memory.

BTW, great work. Hoping you get back to the N8x0 port sometime, so I can use my N800 again. :-)