How do I use RVM and create globally available gems?

I'm running Mac OSX 10.6.4 and have installed RVM. Its been great so far, I really love the way it lets me manage having multiple versions of rails and ruby on the same machine without headaches!

However, I don't want to have to install certain gems (such as passenger) for each setup. Is there a way to share gems between gemsets? I have a 1.8.7@rails2.3.8 и 1.9.2@rails3 , могу ли я один раз установить такие гемы, как пассажир, mysql и capistrano, и использовать их со всеми версиями?