I just upgraded from Lion to ML after the 10.8.2 update. I did a clean install manually reinstalling all my software. So far I like the new OS a lot but I am having one issue. At work when I use ethernet there sometimes it causes the kernel_task in activity monitor to spike to ~20% cpu usage. Not horrible but it heats up my computer and if i'm doing something cpu intensive it gets in the way. I couldn't figure out what was causing it but I think now I have it narrowed down to when ethernet is plugged in. However it isn't consistent. I'm at work right now with ethernet plugged in and everything is normal. But when kernel_task does start acting up unplugging the ethernet stops it and when I plug it back in the kernel_task starts up again. I've attached a screen shot of the console. Highlighted in blue is what happens directly after I plug in the ethernet cable and the kernel_task cpu usage spikes. This isn't a deal breaker problem but it is really annoying and if anyone has any insights i'd love to hear it. Thanks!