At the time of writing there hasn't been an official release of the WCF facility. However, seeing as the Castle project is open source, you can get the sources and compile it yourself.
The sources are stored on GitHub (http://github.com/castleproject/Castle.Facilities.Wcf). You can also get the sources as an archive (zip/tar). Of course you can also use a git client of your choice.
When you have the sources, you have to extract them and then run 'ClickToBuild.cmd'. This will build the sources and put them in the /build/ directory.
As you can see, it's quite easy getting the sources and compiling it yourself. Next up: using the WCF facility to provide you with a service host.