In the USA, there is the National Association of Government Webmasters (NAGW, http://www.nagw.org/).
They actually evolved out of a local e-government webmaster group. Every year they organize a 3-day national conference where you can meet colleagues, vendors and attend interesting presentations. And they organize all kinds of local activities and meetings.
Maybe one of the local groups could pick this up and make it a national thing. I am sure that the NAGW can provide ideas and support.