Surprised by Judgment

In Matthew 25, we see a side of Jesus that some people aren't quite comfortable with. Jesus teaches on judgment - that there will be a final reckoning for all people, that judgment will be made, and that many will find the Son of Man's judgment surprising. His judgment will involve a separation - separating people like sheep from goats - but it will not be on the basis of nationality as most of Jesus' audience would have expected. The dividing line is not Jew and Gentile, but instead follows a fault line created by love for the 'least of these'. What exactly does this mean, and why should it matter for us today? How is this judgment good news, and what does it mean to love 'the least of these'?