The easiest way to run Merb from edge:
$ sudo gem install sake $ sake -i http://github.com/wycats/merb-more/tree/master%2Ftools%2Fmerb-dev.rake?raw=true $ sake merb:clone $ sake merb:install:all
This will install the edge versions of all of the merb gems.
To keep things up to date, navigate to the directory that you ran the commands in and do:
$ sake merb:update $ sake merb:install:all