@babel.localeselector
def get_locale():
    return request.accept_languages.best_match(LANGUAGES.keys())

import datetime
from flask.ext.babel import gettext

@app.template_filter('date')
def _jinja2_filter_datetime(date, fmt=None):
    if fmt:
        return date.strftime(fmt)
    else:
        return date.strftime(gettext('%%m/%%d/%%Y'))