Genesis is based on the Eclipse RCP. As such, it exists as a set of plugins which together constitute the Genesis application.
Versions are given in MAJOR.MINOR.REVISION form.
Incrementing the major component means that backwards compatibility of the published public API has been broken. Note that the Genesis plugins are currently at version 0.0.REVISION, suggesting that none of the API has yet been frozen.
The minor component is incremented for each significant release. When the major component is incremented, the minor component is reset to 0. Again, the Genesis plugins are still in the initial development stream, so the minor component will not be incremented for a while.
The revision component is incremented with each commit to the repository. It is not reset to 0 when the minor or major component is incremented. It may also skip numbers because Subversion repositories use a global revision number (which may be incremented by other projects in the same repository).