Some contacts never show up online. Some are "hidden" (like in MSN), some are services that don't advertise presence, like update@identi.ca.

Nontheless, it's often important, especially with services, to be able to open a chat with that user quickly and easily. One of the most important features of update@identi.ca, for example, is to be able to update your microblog via xmpp.

Consequently, it should be possible to mark a contact as "always shown", so that they show up in the contact list for easy access, regardless of their online/offline status.

This also could apply to statusless VOIP contacts, where it would be desirable to use the contact list as an 'address book' of frequently used accounts.

Note that this is likely distinct (although similar) from the proposed "favorite" virtual group, as that favorite list may still just show the online users. Potentially could be implemented similarly though.