Get the plugin like so...

script/plugin install git://github.com/adamwiggins/yaml_db.git

This command will dump your data

rake db:data:dump

And load it back

rake db:data:load

Beautiful :) More info here http://blog.heroku.com/archives/2007/11/23/yamldb_for_databaseindependent_data_dumps/ and http://stackoverflow.com/questions/490507/best-way-to-export-a-database-table-to-a-yaml-file

Just finishing up brewing up some fresh ground comments...