Not the full destination address but with a bit of google you can figure out where Jeff Garzik lives, call up DHL, pretend to be him, fill in some of the default questions they ask you once you give them the tracking number and change the package destination.

If you do, I'd prefer that you use Jeffs current workplace in Brussels at our offices, we'll hold it for him ;-)

Publishing a tracking number public before the package has arrived is a bad idea.
Sending the tracking number of a package on route to the customer is common courtesy.