I think Techmeme just crawls the sites in their 'network' for cross-linking. For example Techmeme has TechCrunch/Ars/Engadget/Scobleizer/etc in their network an

I think Techmeme just crawls the sites in their 'network' for cross-linking. For example Techmeme has TechCrunch/Ars/Engadget/Scobleizer/etc in their network and if they link within each other then that pushes the story up higher (again, not 100% sure, just making an assumption based on what I've seen). I don't think there is a real-time way to see how many sites are linking to another unless they're being crawled quite often by google/yahoo/technorati OR you have a script installed on their site to see the inbound links and gauge traffic.