I also updated iTunes and Quicktime and still had the AppleMobileDeviceService.exe high cpu problem.
I started iTunes and tried to sync my ipod touch. That got stuck doing backup(Step 1). After reading several other forums, recommended checking the backup folder.
When I checked the backup folder in : documents and settings/username/application data/apple computer/mobilesync/backup/0147a3e...
I saw in the newest folder under the backup folder, the newest item was related to Quicktime.
So I decided to remove Quicktime from my computer.
After doing that, AppleMobileDeviceService.exe cpu dropped to zero.
Now I am downloaded Quicktime from Apple to install from scratch.
After finishing the install, AppleMobileDeviceService.exe is high again.
Then after watching a short video in iTunes, AppleMobileDeviceService.exe cpu dropped to zero.
Anyone else?