I was rapturizing yesterday about the # thing in Twitter and how it seems to have filled some kind of linguistic void for people. It was meant to do a fairly simple thing (group posts about the same event, like blog post tags), but people en masse have adopted it and started using it for a less easily defined, but still very specific effect in both Twitter and the outside world. This is the same process by which any artificially introduced element of language turns into a real part of the language, and... it's just kind of weird. Because it's not really a word or a grammatical arrangement or anything you'd normally think of as being an element of language.
Here is an article that is pretty good about it: How Twitter's Hashtag is Changing Communication. Though I think more proper linguistic study could be done about it. And no doubt is being done right now by the next crop of linguistics thesis students.
And, of course, there's a part about people making a # hand-gesture that reminded me of something I read in the Onion almost a decade ago, proving that really a lot of my brain storage space is...doing very important work: Finger-Quotes Lady Now Doing Hand Parentheses