Here is my command prompt from my .bash_profile. The command prompt detects whether it's in a git project or not and if it is, it indicates the current branch and whether there are un-staged changes pending.

.bash_profile

# RETURN ASTERISK WHEN CHANGES ARE PRESENT BUT UNSTAGED
function parse_git_dirty {
  [[ $(git status 2> /dev/null | tail -n1) != "nothing to commit (working directory clean)" ]] && echo "*"
}

# GET THE CURRENT GIT BRANCH
function parse_git_branch() {
  if [ -d "./.git" ]; then
    git branch 2> /dev/null | sed -e '/^[^*]/d' -e "s/* \(.*\)/[\1$(parse_git_dirty)]/"
  fi
}

# ANSI COLORS
RED="\[\033[0;31m\]"
YELLOW="\[\033[1;33m\]"
GREEN="\[\033[0;32m\]"
CYAN="\[\033[0;36m\]"
BLUE="\[\033[0;34m\]"
LGRAY="\[\033[0;37m\]"
DGRAY="\[\033[1;30m\]"
RESET="\[\033[0m\]"

# BASH PROMPT
export PS1="$DGRAY\w$BLUE \$(parse_git_branch)\n$GREEN\[\e[32m\]λ:$RESET "

NOTE: since checking ./.git is only checking the root directory, the git branch will not show if you are in a sub-directory of a git repo. I sort of want mine to work this way because it's better than calling git branch at every prompt.