Simple Translation Gem
It's hard to say much about such a short code sample, but factories simply encapsulate object creation (wiring up objects), which frees code using them from that responsibility.  In that sense, factories are relevant in ruby too.

However, note that client code would look like this, given your current code:

translator = FreeGoogle::Factory.create


which isn't as readable as it could be.  I think I'd prefer to write something like the following in my client code:

translator = FreeGoogle.new_translator