As I write this, kernel_task has ballooned to 682.8 MB of real memory. I noticed kernel_task yesterday when I had ~2.5GB of free memory (which is odd, because I recently upgraded to 8GB). I quit every application and restarted with "Reopen windows" unchecked. Immediately after restart, kernel_task was 488.1 MB. What's causing this? I have enough RAM that it doesn't matter too much, but I'd really like to be able to prevent this if possible.