I have one caveat about using a twitter wall - I have seen it get kind of nasty. If there are any comments that are kind of critical and they're on display behind the speaker(s).
This is an extreme case, but it's always good to consider what happens when the backchannel becomes the frontchannel and whether the risks are worth it. http://www.zephoria.org/thoughts/archives/2009/11/24/spectacle_at_we.html
Hello everyone:Have any of you ever done a twitter wall for an event? Can you tell me what kind of hardware is required, and where would I get it?Any advice on setting a hash tag for the event, etc?Thanks!Ann