Most of the closed beta testers' data will be wiped in preparation of the open beta phase but faction leader data will remain as is and the developers are working to make a smooth transition of it. Other data that will remain is not known at the moment as Duplex has only described it as a wipe of "most" data.
The game is yet to be done as described in the announcement but the game is most likely ready for a stress test from open beta testers. And more or less a way to tell us they are still around and they are making progress as they have fallen under the radar of most MMO gamers.
Full announcement below:
Open Beta Announcement
The time has come. We are finally releasing Face of Mankind for open testing by all interested parties in our Open Beta phase, to be officially opened on the 5th of December, 2009. The game may not yet be perfectly balanced, nor with all the features our Closed Beta testers would have liked to see, but we will perhaps never reach a state of perfection without widespread testing with an unrestricted playerbase. As such, this release of Face of Mankind’s Open Beta is simply a matter of necessity for us to reach newer and greater heights.
There will be a wipe of most things from this final phase of Closed Beta, but we have decided to keep the faction leader structures in place to facilitate a smoother transition, and to ensure that players, both new and old, will have some semblance of organization to get them settled into the world of Face of Mankind.
We are also including a comprehensive tutorial for your perusal. Face of Mankind has gone through many transformational changes in myriad aspects of the game, ranging from combat, to the final battle mechanics, and various new features, just to name a few. Even players from the previous incarnations of Face of Mankind before we reopened this new version of Face of Mankind will very likely feel like a proverbial duck out of water. Hence, we highly recommend you take a look at this tutorial to get you up to speed on Face of Mankind, whether you are a veteran or completely new to the community.
On behalf of Duplex Systems, neXeon Technologies, and all of the Face of Mankind staff, I hereby welcome you to join us in Face of Mankind for our final stage of testing before we go live. Please, immerse yourself in the diverse and expansive worlds Face of Mankind has to offer, the intricacies of the politics between the factions and the player government, and above all, enjoy yourselves!
-duplex
You can find the original forum post here.
And the open beta client is available at Fileplanet.