I had my (week 31) MacBook for about a week before Apple released the firmware update. It ran fine; no noise and it wasn't very hot. The temperature stayed in the low 60C range usually.
I ran the update when it appeared on Software Updater. At first it didn't seem to make a difference, however, when I next woke my computer up from sleep I noticed that the temperature reported by CoreDuoTemp had dropped to 20C and stayed that way for hours unless I restarted. I mentioned this in the firmware update thread; I'm wondering if it's a problem with CoreDuoTemp or my computer's temperature sensors.
Just 30 minutes ago I sat down at my desk and ... moooooooooooooooo. It's very annoying. My only guess is that the firmware has something to do with it. To find out, I want to know if it's possible to uninstall the update. Anyone?