I've recently noticed that kernel_task is constantly using 11% of CPU on my 2.53 GHz MacBook Pro with OS X 10.6.6. Try disconnecting from your network. You may have some device that is actually ...

MacFixIt reader "Martin V." writes in to alert us about an ongoing issue with his MacBook Air. The process 'kernel_task' uses an inordinate amount of system resources causing his system to run ...

According to an old thread (10 months at the time of writing) over on Stack Exchange, charging a MacBook Pro using the ports on the left side can cause high kernel_task CPU usage and overheating.

I've noticed that as I leave the system on longer, kernel_task uses more and more memory, CPU Usage doesn't really go up but right now its consuming about 86 megs of real memory on a 1gig of ram ...