I haven’t yet started using Twitter, but I have a number of Facebook friends who feed their Tweets to their Facebook status updates (is that enough Web 2.0 references in one sentence?), and I’ve wondered about the meaning of the hash mark (#) that people include in their Tweets. For example “I was talking on my #iPhone…” or “Going to a #Boulder Media Women event…”. If you’re also wondering, here’s an easy to follow explanation from Kristine Wirth’s blog. In brief, the hash marks are a sort of keyword tag in Twitter, and if you’re willing to sacrifice one of your precious 140 characters, the term that you tag with the hash mark will then show up on the hashtags website. Once you’ve visited the hashtags website, you can then add the decidedly Web 2.0 term “real-time news community” to your vocabulary!