As the project's blog notes, it means sites serving under 25 million ads a month can now get control of their ad serving, free, without the cost of running the software themselves.
There are also going to be "professional" and "enterprise" packages for larger sites. Officials are hanging out in their own chatroom today to answer your questions.
This follows by just two weeks the alpha release of OpenX Market, aimed at letting advertisers bid directly for ad inventory hosted on OpenX.
It's important to note that this just won't impact Web sites, but RSS feeds as well, where Google has recently begun hosting larger, more interactive ads.
Which is a great place to discuss the competition. Can open source hope to compete with Google in this area? Can it deliver the kinds of features and functionality Google offers?
We can also look at this another way. Would not some modest success for OpenX help Google keep the antitrust dogs at bay?