Some folks are experimenting with using Wiki to build websites. I particularly like what Matt Haughey did with PHPWiki and a bit of CSS magic dust. Looks nice, eh? [Via Seb's Wikis are Ugly? post at Corante]
Janne Jalkanen's Wiki-based Weblog is interesting too. Hmm. Maybe blog API(s) can be used for Wikis too. That reminds me, shouldn't Wiki formatted text have their own MIME type? Is there one? "text/wiki"? For now, different dialects of Wiki formatting rules will have to be accounted for like "text/wiki+moinmoin".
Update #1: I found this nice page listing Wiki and Weblog hybrids.