I hadn't heard of Hudong before. This article by Rebecca Fannin calls
it "China's Wikipedia" and says it has a 95% market share and more
"than 5 million entries from 3.6 million contributors."
http://www.forbes.com/sites/rebeccafannin/2011/08/23/why-draper-funded-chin…
English Wikipedia has had an article about Hudong since 2008, and
Chinese Wikipedia has had an entry since 2007. According to Wikipedia
the software has some interesting social networking features, but is
not free software although the source may be downloaded freely.
This provides an interesting chance to peer through the looking glass.
Although apparently monolingual, Hudong is comparable in size to
Wikipedia at the same age. It's a commercial startup and runs on
advertising income. Already one can see that it has followed a
different path from that of Wikipedia.