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 Button on your team explorer.
If you don't like the busy view in in your team explorer, you can uncheck the "Display as Button on Team Explorer option.
It starts appearing as a navigation link in the "My Work" button of the Team Explorer window.
Clicking on the link will display all your shelvesets. Simply select the shelvesets you want to compare and click the compare button.
If you want to compare the shelveset with that of another user, simply type in the other user's name and his/her shelvesets will start to appear in the list as well.
All the source code of the extension has been uploaded to codeplex at http://shelvesetcomparer.codeplex.com.