I say this not because of how it works or the people using it. My prediction is based on speaking to vendors who are releasing software and services for the cloud under open source models. As part of my standard question I usually ask them something like "why open source and why now?" Many of them have candidly responded to me that the reason they have released their software under an open source license is that they wanted to be part of the Open Stack and so had to be open sourced.
That is pretty powerful proof if you ask me. Open Stack is having such an impact that it is causing softare companies to go open source so they can be part of it. That means these companies have decided that being part of Open Stack is critical to their success. If they think it is critical to their success, then Open Stack is indeed making huge progress.
That is a a good thing for us. We get the benefit of having more, better open source software for the cloud.
There is good reason for this too. It is becoming more and more clear that much of the cloud is being built on open source. Open source is proving not only secure, but reliable and scalable as well. For those critics who still doubt wether open source is enterprise ready, I don't know what better proof you need.
Open Stack is coming to represent the best that open source for the cloud has to offer. Their certification and inclusion process is weeding out would be pretenders and making sure that what is labeled Open Stack is the very best. It is becoming the "Good Housekeeping" seal of approval for Cloud Software.
In hindsight, what a great move by Rackspace to involve NASA and open up the stack. I think they have positioned Open Stack to be dominant in the cloud. What LAMP was to the data center, Open Stack will be to the cloud.