While you can download previous releases of Brail from this page, all future releases will be part of the Castle Project so head there to check for new stuff and a lot of cool ideas beyond that.
To get the source code from the repository, just point you favoraite Subversion client (or just your browser to: http://svn.castleproject.org/svn/castle/trunk/MonoRail/Castle.MonoRail.Views.Brail/
The downloads below are provided in case you need them, you shouldn't use them to setup a new site, you should use the Castle distribution for that.