Is there any advantage using rvm?
in ruby, as in many languages you can have conflict between libraries, also since rails and ruby are open, gems came from everywhere so is hard to keep and eye on versions, another problem is that rails changes very fast because the community is very engaged and active, all this causes a problem, your libraries change often, so if lets say you have one project his week using a certain gem version maybe by next week when you are going to make a new project you can use a newer version of you favorite gem, but you soon notice there is a conflict since the new gem is not backwards compatible and cant be use in the old project or now it only works with a previous version of ruby and you old proyect needs a huge port to make the leap. All this could be a problem is there was no rvm, rvm creates a separated environment for every ruby you install and you can also have gemsets which isolate gems into folder that you can assign to each project, so now you can have
rvm use ruby1.8.7@gemsold
for the old project and
rvm user ruby1.9.2@gemsnew
for the new proyect and never worry about a conflict again.