Are online and can be downloaded from LATZ.org.
Looks like all of the original Infocom text adventures are here and you can download the interpreter to play them. Sweet. This saves me the trouble of trying to find a 5 1/4″ drive so I can play my copies.
On a related note, here’s a Wired article discussing the fusion of AIM, an AIMbot, and the Infocom Z files to allow playing these files using AIM. Cool. Now there needs to be an MSN bot to do the same thing.