Brian:
Yes, hashtags (#) are used to make certain phrases/topics much more easily searched on Twitter. Facebook has started using them, just in the last year I believe, to create a kind of Twitter crossover experience, since so many people automatically have their posts go straight to both Facebook and Twitter.
Anyone can create a hashtag. But if you're the only one using it, then it's not going to create any cross-pollination across Twitter. And because they're specifically designed for Twitter, where every tweet is limited to 140 characters, you wouldn't want to hashtag #IAmtheLeadingExpertonMyOwnOpinion, because that would seriously cut into your character limit.
Many (most? all?) corporations have automatic searches set up so that any Tweets that include a hashtag of their corporate name will be found and read. That's how a lot of folks are getting customer-service issues handled these days: They tweet about a problem, include the corporate name as a hashtag, and they know that that tweet is going to be seen by the company. And, often, they get responded to faster than any other contact method, because it's very easy for news (both bad and good) to spread across Twitter within minutes.
To bring this back to our hobby. . . Say you tried a new MacBaren blend and wanted to praise it on Twitter or Facebook. You might post: "Loved the new XXX blend from #MacBaren. Better than #ThreeNuns!" That way, anyone who's wanting to follow tweets about MacBaren and/or #ThreeNuns will have your post show up in their feeds. Without the hashtag symbol, they'd have to specifically search for tweets containing those words; with the hashtag, Twitter and Twitter-client apps (Tweetdeck, Tweebot, etc.) will find it automatically.
I just checked, and there's currently an active hashtag for #pipesmokers. Plug that into Twitter, and you can see all the recent tweets that used it. That can lead you to folks you'd like to follow on Twitter, articles and news about pipe smoking, etc. But, of course, you have to have a Twitter account for this. (Which is free.)
Bob
