Awesome! Does this mean you'll accept patches and stuff through pull requests? If so, maybe you should put up a small FAQ about the use of github for roundcube developers. I use github on another project, and some stuff just keeps being asked, like "how do i remove all my local patches and sync with the remote repository'. Im sure there are some knowledgable github ninjas here that could help out.
Github takes a whole new way of thinking with regards to development, it's totally unlike subversion. It can confuse people quite a bit at the beginning :)
Cor