Great but badly documented piece of software
I am quite new to RoR (Ruby on Rails), but this piece of software is amazing. After some time you need to learn the concepts, your efficiency will increase rapidly. on average you can expect to code 5-15x faster than you did with i.e. PHP (my previous language of choice).
i can recommend this package although the documentation is really bad. but i think this will change when the project will release version 1.0 soon. and so long you should visit their irc channel.
i think that's all i need to say. this project is amazing. and the provided extra projects offer almost everything you want if you want to provide a nice web interface for your mailserver.
except the high requirements for the framework installation, everything is easily setup.
so enjoy it. and have a look at the google coding summer projects as well as the horde bounty hunt ;)