Add following code to ~/.bashrc, then run source ~/.bashrc

__perlbrew_ps1()
{
    if hash perlbrew; then
        local v="$( perlbrew list | perl -lane'print $F[1] if /^\*/' )"
        if [[ -n "$v" ]]; then
            printf "${1:- (%s)}" $v
        fi
    fi
}

PS1='[\u@\h$(__perlbrew_ps1) \W$]\$ '

Your PS1 will looks like:

[hlin@desktop-hlin (perl-5.10.1) ~]$