Stick this in your bashrc and don't wonder what branch/ruby/gemset you're using

.bashrc

# Git and RVM prompting
function git-current-branch {
    git branch 2> /dev/null | sed -e '/^[^*]/d' -e 's/* \(.*\)/(\1) /'
}
export PS1="[\$(~/.rvm/bin/rvm-prompt v p g)] \$(git-current-branch)$PS1"

You could use git branch 2> /dev/null | sed -n 's/^\* //p' and put the parens in your $PS1. :)