We're seeing quite a few new C++ user groups being formed, and so it's a good time to link to this timely article by Jens Weller:

Founding local C++ User Groups

From the article:

Lets start into the discussion on founding user groups, there is in my opinion different approaches to get started, but I don't want this to be a discussion, so I'll just list what I think is right. First I think that a C++ User Group should be local, which means its usually for a certain region. From my expierence, people are willing to travel up to 70km one way to a user group meeting. So in order to get started, I think you'll need the following four points:

• People
• Location
• Topics
• Date

...