The Shelveset Comparer extension allows you to compare the content of two shelvesets without needing to unshelve any of them. You can use it compare youers as well as anyone else's shelvesets.
Once installed the extension appear as a Navigation Link in the "My Work" section of your Team Explorer window and as a team explorer button.
Clicking on the navigation link or the compare shelveset button will display all your shelvesets. Simply select the shelvesets you want to compare and click the compare button.
If you want to compare shelvesets of two different users, you can type in the user names in the text boxes and all their shelvesets will start appearing in the list. To compare the shelvests, simply select the two of them from the list an click on teh Compare button.
All the source code of the extension has been uploaded to codeplex at http://shelvesetcomparer.codeplex.com.