Spread the word. Become a supporter of the webUML initiative. Put a badge on your site, blog, ... Talk to your friends and colleagues about this Call for Action and invite them to also subscribe and support it. The first thing we have to do is create awareness. We need to show the people who define and create the tools we use on a daily basis, that the time has come to leverage the collaborative power of the internet. (See what others are saying about the webUML initiative)
Discuss these ideas. Write about these ideas on your blogs, discuss with your readers about the possible merits and pitfalls. Once we've created awareness we need to come up with solid solutions. We don't want a second decade of darkness. We want to get it right this time. We will set up an online forum very soon and invite everybody to join in the discussion. So check back for that.
Act now. If you are a developer of a UML-enabled tool and want to prepare your tool for the new age, now is the time. Or, if you happen to know people working on such a tool, point them in this direction. We want to become a hub between all these people, allowing them to jointly define the new way of dealing with UML online.