Good questions.
What goes on at these events?You are limited only by your own imagination. Based on what I've seen first hand, you can:
* Socialize with other great people interested in Bitcoin: Newcomers, gurus and early pioneers, writers, entrepreneurs, economists, investors, activists, etc. Celebrities have been known to drop in on these events. Don't see someone you think should be there, just bring them along.
* Learn more and teach others.
* Buy, sell, barter. Keep the coins circulating in the community.
* Talk about how to spread Bitcoin to more people, more businesses.
* Engage in fascinating conversations.
* Demonstrate or pitch your latest Bitcoin project.
* Hold presentations and debates.
* Indulge in good food and drink.
* Plot your next Bitcoin heist (just kidding).
How do I organize one in my community?You can just do it. Here are some tips.
1. Find a location. It helps if the meeting place is accessible and has WiFi. They do not have to accept Bitcoin yet. The next date for Bitcoin Wednesday is August 7.
2. Add your city to the list -- at the end of this thread, or update the Bitcoin Wednesday wiki here:
https://en.bitcoin.it/wiki/Bitcoin_Wednesday3. Invite local Bitcoin people. You can find them on the regional section of this forum, on LocalBitcoins.com, on Reddit
http://www.reddit.com/r/Bitcoin/ on Meetup sites, on Facebook, on Twitter.
4. Show up and have fun.