I was getting this same error for an iPhone and two iPads after updating to iTunes 10.2.1, and installing Xcode 4 under Mac OS X 10.6.6.
Here's what I did to resolve the issue (NOTE: These steps came directly from an Apple Support document which outlines removing iTunes completely from your computer. However, since I wasn't willing to do this ALL the outlined steps, I only applied the steps below):
1. Disconnect any iOS device(s) from the computer.
2. Move the iTunes application icon to the Trash.
3. From the Finder, choose Go > Go to Folder
4. Enter (without quotes) "/System/Library/Extensions" and then click Go.
5. Locate the file "AppleMobileDevice.kext" and drag it to the Trash.
6. Choose Go > Go to Folder.
7. Enter (without quotes) "/Library/Receipts/" and then click Go.
8. Locate the file "AppleMobileDeviceSupport.pkg" and drag it to the trash. Note: This file may not be present in Mac OS X v10.6 or later; skip to the next step if this is the case.
9. Restart your Mac.
Since I was very nervous about losing data, I did NOT empty the Trash.
After restarting, I downloaded the latest version of iTunes and installed it:
http://www.apple.com/itunes/download/
Once complete, I opened iTunes and was quite pleased to see that all my data was intact. I then plugged in an iPad and voila -- problem solved. iTunes did not generate the "iTunes was unable to load provider data from sync services" error and it completed a backup, then sync'd without error. I did the same for my iPhone and finally my wife's iPad.
Hope this helps!