This is a bash script that wraps git and lets you implement pre- or post-command hooks that apply to git globally (not per-repository). Out of the box, this script has a post_clone and post_init hook that do the same thing: prompt you to verify that the author information (user.name and user.email) are correct for the given repository -- prevent…

git

#!/bin/bash
#
# This script wraps git, so install it somewhere such as ~/bin where
# it will be found by your shell before the actual git executable.

set -e

# Extract the command from a git command line
function get_command {
    while [[ "$1" =~ ^- ]]; do
        shift
    done
    echo $1
}

function pre_command {
    command="`get_command "$@"`"

    # Pre-command hooks could go here
}

function post_command {
    command="`get_command "$@"`"

    # Post-command hooks
    case $command in
        clone) post_clone "$@" ;;
        init) post_init "$@" ;;
    esac
}

function post_clone {
    # Skip past irrelevant parameters
    while [[ "$1" =~ ^- ]] || [ "$1" = "clone" ]; do
        param="$1"
        shift
        if [ "$param" = "--" ]; then
            break
        fi
    done

    # We only need to know the target directory
    repo="$1"
    dir="$2"
    if [ "$dir" = "" ]; then
        # Directory not passed, derive dir name from repository URI
        dir="$repo"
        dir="${dir##*/}"
        dir="${dir%.git}"
    fi

    configure_author "$dir"
}

function post_init {
    last="${@: -1}"
    if [ "$#" -le 2 ] || [[ "$last" =~ ^- ]]; then
        dir="."
    else
        dir="$last"
    fi

    configure_author "$dir"
}

# Rationale: It's not hard to run git config user.email, etc., but I often
# forget to do it and accidentally commit to a repository with the wrong
# author email set. This will ensure that after a clone or init, I'm prompted
# to verify the author configuration.
function configure_author {
    dir="$1"
    pushd "$dir" >/dev/null
    echo "--"
    echo "Configuring author for this repository..."
    echo -n "Author name: [`"$GIT" config user.name`] "
    read name
    if [ -n "$name" ]; then
        "$GIT" config user.name "$name"
        echo "  [$dir] git config user.name \"$name\""
    fi
    echo -n "Email address: [`"$GIT" config user.email`] "
    read email
    if [ -n "$email" ]; then
        "$GIT" config user.email "$email"
        echo "  [$dir] git config user.email \"$email\""
    fi
    popd >/dev/null
}

# Assuming this script is called 'git', find the next available 'git' command
# via 'which'. Override this if you want to hard-code a different path.
GIT="`which -a git | awk 'NR==2 {print}'`"
if [ "$GIT" = "" ]; then
    echo "git executable not found"
    exit 1
fi

# General: Do not run hooks for --help
if [ "${@: -1}" == "--help" ]; then
    "$GIT" "$@"
else
    pre_command "$@"
    "$GIT" "$@"
    post_command "$@"
fi

Hi Mike,
thanks for that script!
I created my own based on your basic idea, maybe you can benefit from my work too:
https://github.com/benjaminfuchs/git-wrapper
Greeting,
Benjamin