No, don't do this. The people maintaining your code will hate you if everything is an unnamed lambda.

A better way to do it is to take your core data structure, in this case a user, and turn it into a class, dictionary or named tuple. Classes are the best way - there are all sorts of ways to put a nice interface on them.

For example:

   class User(object):
        def __init__(self, name, post_count):
            self.name = name
            self.post_count = post_count

        def __repr__(self):
            return '<User name="%s", post_count="%s">' % (self.name, self.post_count)

        def __cmp__(self, other_user):
            # larger is better
            return -cmp(self.post_count, other_user.post_count)

    # set up data
    users_ = [["user1", 500], ["n00b", 15], ["thebestuser", 177]]
    users = []
    for user in users_:
        users.append(User(*user))
    print users

    # sort users by post count by default
    print sorted(users)