That seems to be the case with tags. Uumh, they are ambiguous, did you know that?
First I think it was Technorati, they came up with the concept of WTF .
WTFs are short blurbs that explain the buzz around people, things, or events—why the hot topics are so hot—and you can vote the best ones to the top.
Now I saw it in del.icio.us, you can create a tag description to explain to others what is it that you really mean by your tag (it's really getting from being personal to being public). Very interesting. You now add metadata to your tags (e.g. meta-metadata) to describe the meaning by an author of that tag.
Well, if this trend keeps going, soon we can expect to fill-in all the LOM metadata fields ;) No, seriously, Sir Berners-Lee must be exited about this turn!