Doing some investigation.....
Note I installed Xcode 4.6DP2 on 25th Nov. Not sure my install went totally to plan - a few missing folders:
http://f.cl.ly/items/26402T1R1Y330E3A211n/Text%202012.11.28%203:35:55%20PM.txt
Some diffs:
From 24th Nov MobileDevice.Framework = AppleMobileDeviceHelper - version.plist
<key>BuildVersion</key>
<string>40</string>
<key>CFBundleShortVersionString</key>
<string>5.0</string>
<key>CFBundleVersion</key>
<string>889</string>
<key>ProjectName</key>
<string>Sync</string>
<key>SourceVersion</key>
<string>894000000000000</string>
From 25th Nov MobileDevice.Framework = AppleMobileDeviceHelper - version.plist
<key>BuildVersion</key>
<string>111</string>
<key>CFBundleShortVersionString</key>
<string>5.0</string>
<key>CFBundleVersion</key>
<string>889</string>
<key>ProjectName</key>
<string>Sync</string>
<key>SourceVersion</key>
<string>894000000000000</string>
New build version
From 24th Nov MobileDevice.Framework - version.plist
<key>BuildVersion</key>
<string>22</string>
<key>CFBundleShortVersionString</key>
<string>555.42</string>
<key>CFBundleVersion</key>
<string>555.42</string>
<key>ProjectName</key>
<string>MobileDevice</string>
<key>SourceVersion</key>
<string>555042000000000</string>
From 25th Nov MobileDevice.Framework - version.plist
<key>BuildVersion</key>
<string>5</string>
<key>CFBundleShortVersionString</key>
<string>555.40</string>
<key>CFBundleVersion</key>
<string>555.40</string>
<key>ProjectName</key>
<string>MobileDevice</string>
<key>SourceVersion</key>
<string>555040000000000</string>
New build version and ShortVersionString
The Xcode 4.6DP2 Contents/Resources/Packages has MobileDevice.pkg. In there:
<bundle CFBundleVersion="282" CFBundleShortVersionString="282" SourceVersion="282000000000000" id="com.apple.AirTrafficHost" path="./System/Library/PrivateFrameworks/AirTrafficHost.framework"/>
<bundle CFBundleVersion="260" CFBundleShortVersionString="5.0" SourceVersion="261000000000000" id="com.apple.DeviceLinkX" path="./System/Library/PrivateFrameworks/DeviceLink.framework"/>
<bundle CFBundleVersion="555.42" CFBundleShortVersionString="1.0" SourceVersion="555042000000000" id="com.apple.MobileDevices" path="./System/Library/CoreServices/CoreTypes.bundle/Contents/Library/MobileDev ices.bundle"/>
<bundle CFBundleVersion="889" CFBundleShortVersionString="5.0" SourceVersion="894000000000000" id="com.apple.SyncServices.AppleMobileDeviceHelper" path="./System/Library/PrivateFrameworks/MobileDevice.framework/Versions/A/Appl eMobileDeviceHelper.app"/>
<bundle CFBundleVersion="889" CFBundleShortVersionString="5.0" SourceVersion="894000000000000" id="com.apple.SyncServices.AppleMobileSync" path="./System/Library/PrivateFrameworks/MobileDevice.framework/Versions/A/Appl eMobileSync.app"/>
<bundle CFBundleVersion="3.3.0" CFBundleShortVersionString="3.3.0" SourceVersion="221001000000000" id="com.apple.driver.AppleMobileDevice" path="./System/Library/Extensions/AppleMobileDevice.kext"/>
<bundle CFBundleVersion="2.3.6" CFBundleShortVersionString="2.3.6" SourceVersion="87002000000000" id="com.apple.driver.AppleUSBEthernetHost" path="./System/Library/Extensions/AppleUSBEthernetHost.kext"/>
<bundle CFBundleVersion="555.42" CFBundleShortVersionString="555.42" SourceVersion="555042000000000" id="com.apple.mobiledevice" path="./System/Library/PrivateFrameworks/MobileDevice.framework"/>
Diffs: http://cl.ly/LC6x/o
Going to try this (I have a full SuperDuper clone for safety):
sudo mv /System/Library/PrivateFrameworks/AirTrafficHost.framework ~/Desktop
sudo mv /System/Library/CoreServices/CoreTypes.bundle/Contents/Library/MobileDevices.bu ndle ~/Desktop
sudo mv /System/Library/PrivateFrameworks/MobileDevice.framework ~/Desktop
mv /private/var/db/receipts/com.apple.pkg.MobileDevice* ~/Desktop
Then reinstall /Applications/Xcode.app/Contents/Resources/Packages/MobileDevice.pkg
......
Seemed to go OK (http://f.cl.ly/items/0t270n250U381r030F3S/Text%202012.11.28%204:08:59%20PM.txt), but some errors re missing kexts:
Nov 28 15:55:19 Jamess-iMac.local installd[43817]: preinstall: (kernel) Kext com.apple.driver.AppleMobileDevice not found for unload request.
Nov 28 15:55:19 Jamess-iMac.local installd[43817]: preinstall: Failed to unload com.apple.driver.AppleMobileDevice - (libkern/kext) not found.
Nov 28 15:55:19 Jamess-iMac.local installd[43817]: preinstall: (kernel) Kext com.apple.driver.AppleUSBEthernetHost not found for unload request.
Nov 28 15:55:19 Jamess-iMac.local installd[43817]: preinstall: Failed to unload com.apple.driver.AppleUSBEthernetHost - (libkern/kext) not found.
However, starting iTunes, no error dialog or system errors and I able to backup to iCloud and my Mac.
The only error I see is:
Nov 28 15:57:12 Jamess-iMac.local AppleMobileDeviceHelper[43919]: 43919:2089484672|BackupCommon.m:_canHandleManifestWithVersion| ERROR: Denying NULL inner manifest version
Not sure how serious that is, will keep on investigating.