Upgrade RVM and now PATH is broken
It is not an issue with rvm, but with homebrew:

Since 15th of December 2013 zsh is not longer build with the --enable-etcdir flag by default. Therefore /usr/libexec/path_helper is no longer used to initialize $PATH and all path in /etc/paths as well as in /etc/paths.d are completely ignored. (I know, I just found out myself and am speechless as well.)

Therefore either run brew update; brew reinstall zsh --enable-etcdir or add the following to your .zshrc:

if [ -x /usr/libexec/path_helper ]; then
    eval `/usr/libexec/path_helper -s`
fi


For more information on why this was removed, check this ticket on github.