Rake files are just ruby files[1], so it would be nice to have ruby-mode enabled for them automatically. From [2] and [3], they're named either [Rr]akefile or *.rake. [1] http://docs.rubyrake.org/user_guide/chapter03.html [2] http://docs.rubyrake.org/user_guide/chapter02.html [3] http://rake.rubyforge.org/doc/command_line_usage_rdoc.html
I've added support for this in ruby-mode-2.1.2.