(Is WagNet synonymous with this?)

InterWiki is a general term for features that interconnect wikis (and other kinds of sites; inter-site might be a better term). Such as:

• Namespace Cardtype for Mounting Wagns - suggests plusses — as the natural markup for inter-site links.
• implement SisterSites
• InterWikiLinks
• External inclusion
• Multi-wiki search
• Multi-wiki backlinks
• implement NearLinks

Lion Kimbro's LocalNames microformat already handles NearLinks and InterWikiLinks, and could easily be built on to handle listing a wiki's connection to other sites using these other features.

Relevant tickets