.bash_custom_prompt

export PS1='\[\e]0;\u@\h: \w\a\]${debian_chroot:+($debian_chroot)}\u@\h:\w$(tag)\$ '

gistfile1.txt

Prompt output:
lewisd@transistor:~/projects/lp-webapp\[\][master(1)]\[\]$ 

tag

#!/bin/sh


# Check CVS
if [ -f ./CVS/Tag ]; then
    tag=`cat ./CVS/Tag | awk '{ print substr($0,2) }'`

# If not CVS, then check SVN
elif [ -d .svn ]; then
    svnInfo=$( svn info | grep --colour=never 'URL' | sed -e 's#URL: http://svn.riptown.com/##g' | sed -r -e 's#(.*)/(trunk|branches|tags)/(.*)#\2/\3#g' )
    
    # Is it the trunk?
    if echo $svnInfo | grep --colour=never -q '.*/trunk/'; then
        tag=''
    # Is it a branch?
    elif echo $svnInfo | grep --colour=never -q 'branches/'; then
        tag=`echo $svnInfo | sed -r -e 's#branches/([^/]*).*#\1#g'`
    # Is it a tag (i.e. version)?
    elif echo $svnInfo | grep --colour=never -q 'tags/'; then
        tag=`echo $svnInfo | sed -r -e 's#tags/([^/]*).*#\1#g'`
    fi;
fi;

#hg_branch=`hg branch`
#if ( "$hg_branch" != "default" ); then
#	tag="$hg_branch"
#fi

if ( git branch > /dev/null 2>&1 ); then
	tag=`git branch | grep "^\*" | sed "s/^\* //"`
	commits=$(git log origin.. 2>/dev/null | grep ^commit | wc -l)
	exclam=$(git status --porcelain | grep -qv "^??" && echo "!")
	if [ $commits -gt 0 ]; then
		tag="\[$(tput setaf 1)$(tput bold)\][$exclam$tag($commits)$exclam]\[$(tput sgr0)\]"
	else
		tag="\033[1;32m[$exclam$tag$exclam]\033[0m"
	fi
fi

#Print the tag out if it's not empty
[ -n "$tag" ] && echo $tag