At the moment, the Castle Project is actually host to a number of separate projects. Monorail and Active Record for example, work extremely well together but Monorail does not require Active Record; the same can be said for Windsor.
Previous releases of Castle have contained all of the child projects in one package. In future, this may not be the case. The Castle PMC have decided to split each project off, while still keeping them under the Castle banner. This has the immediate advantage than a Windsor release does not have to wait for a Monorail release, which is surely going to increase the mobility of Castle as a whole. While some sections may lag behind for a while, segments are free to move at their own speed.
It's been a while since a full Castle release, and I feel that many developers wait for such releases before adopting a project. More frequent official versions of the Castle components could increase adoption and interest in the overall brand, which can only be a good thing.