Go to the trade show web site and see if there is a mention of it. If you have a following on Twitter you can ask the people if anyone knows it. If you don’t find a mention, contact the people who run the show, and if they say there isn’t one (or ask you what a hashtag is) create one yourself. Pick a short phrase, usually an acronym, and add the year. For example, at last year’s BlogWorld conference, the hashtag was #BWE09. This hashtag allows you to go on your iPhone or BlackBerry, or twitter.com and see what people are saying about the conference.

You can search this hashtag to interact with people who will also be at the show. You can do this with people who will be attending and also with other vendors. It is amazing what can come out of new relationships with other vendors! When you engage with other vendors before the show, not only can potential business partnerships develop, but it can make the show much more enjoyable when you know other people with booths. They can do everything from bring your lunch when you’re the only person running your booth to potentially watching your booth while you run to the bathroom. There’s nothing harder in a trade show than to be a one-person show at your booth, but it’s a little bit easier when you can find a few friendships beforehand to rely on each other.

Now if you start to see conference chatter on Twitter with the hashtag, this isn’t an invitation to spam everybody who’s going by saying in all caps “COME SEE US AT THE SHOW!!” You need to use the same engagement principles that you would use during normal interaction on Twitter. Start talking to them in a conversation and ask them if it’s the first time at the show. Give them some suggestions as to what parties they should go to afterward. Whatever it is, get the conversation going and engage with them.

Another fun way to use Twitter during a trade show is to have contests that are live. Tweet something like “the first person to come up to our booth wearing a red shirt and saying the phrase, ‘I saw this on Twitter,’ wins a free iPod nano,” or something. Do that once a day and you get a nice amount of buzz going if your conference and attendees are Twitter-friendly.