Lotsa people are having serious memory leak problems with Aperture 3—even our Wilson, who woke up this morning to find that Aperture had eaten his entire hard drive, using it all for virtual memory.
Apple's in "no comment" mode. Which hopefully means "no comment because we're so busy working on a patch." [CW]
DISCUSSION
If it's gobbling it up for virtual memory, won't a restart release it?
Maybe a simple shut down at the end of the night, or restart in the morning if you been processing RAW data all night is the fix.
I honestly don't know. I don't use Aperture.