The tagging feature is new to Slashdot, but I've heard of it before and have been thinking about checking it out. Today I tried a few Google and Freshmeat searches, but variations of "tag" have so many meanings I can't find much among MP3 ID3 editors, retail merchandise tagging supplies and various other IT meanings of "tag".
Does anyone have links to some open sources CMS'es that have tagging support, or perhaps links to some papers and discussions about keyword tagging for blogs or knowledgebases?
Ultimately I'd like to create a sort of user-rated knowledgebase based on some of the sites I visit. The knowledgebase might accept queries, return some summary information and link to the source sites for detailed info.
UPDATE: Ah-ha. While composing the above I came up with "keyword tagging" differentiate between the other tags. It occurred to me I should plug that into Google. Folksonomy is apparently what I'm talking about, and that search and the Wikipedia page I think will send me to the info I need. Not sure yet about open source CMS or knowledgebase software supporting it.