When using MongoRecord a configuration such as "has_many :name, :class_name => 'Somemodule::Someclass'" will fail with the following error:

/opt/local/lib/ruby/gems/1.8/gems/mongo_record-0.1.2/lib/mongo_record/base.rb:196:in `const_get': wrong constant name Somemodule::Someclass (NameError)
from /opt/local/lib/ruby/gems/1.8/gems/mongo_record-0.1.2/lib/mongo_record/base.rb:196:in `has_many'
from test_modules.rb:13

This is because the Kernel.const_get call will not go any further than the top-level. You may wish to see http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/293822 for some discussion regarding the issue and some possible solutions .