Yes, you need to change your Intrepid Partner Repository to the Hardy Partner Repository. Open up Software Sources, and on the Third Party Software tab, edit the http://archive.canonical.com/ubuntu intrepid partner line changing "intrepid" to "hardy". It will work even though you are using the hardy repo. You can change it back after installing if you want, but I'm not sure there's any point. After doing this you can install the zdesktop package.
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