I think that there are a few reasons they haven't released anything yet.
First off, the plugin and the other resources probably need a lot of cleaning up before they're ready for public consumption. When you have an internal tool, you can make it as messy as you want, because nobody else is going to see it, and if it doesn't work, the guy who wrote it is sitting right next to you, so he can fix it. Now that they are going to release the plugin to the public, Cyan needs to clean it up and make it a clean, easy-to-use, bona-fide plugin. If they were to release it now these forums (and their inboxes) would get a flood of emails complaining about broken things.
Secondly, Cyan might be fixing up security issues in the server/client/plugin code. Before, we had no access to the source code, so the possibility of someone hacking a server was very unlikely. Now it could conceivably be pretty easy, so perhaps Cyan is taking the time to ensure that there are solid defenses against hacking in place before releasing.
Lastly, there are probably some legal issues surrounding the release of this code, which they need to sort out before they can go ahead.
Making a project open source that's been private for 6+ years takes a lot of work, try to be patient!

We'll have those tools before 2010, and it will be worth the effort.