It's nice to see a directory like that, although it's unfortunate that you can't simply click on the person's twitter name to see their page. Perhaps this was done to counteract spammers because if live links were allowed the directory might be rapidly overrun with spammers looking for SEO. I don't know... the good news is that Twitter names are all short.
Do you use Twitter and are interested in finding people on Twitter to follow related to telephony, VoIP, Asterisk, communications, etc? Well the folks over at the VoIP Users Conference have put together a website that provides a directory of twitter users related to those topics. If you'd like, you can add yourself using this form.