GEZA VERMES fisks the traditional Christmas story in the London Times:

The real Christmas story
Geza Vermes
A close reading of Matthew shows the emotional truth of the Nativity
There are three variations on the theme of Christmas. In addition to the potpourri of the traditional Nativity story, the careful reader of the New Testament can discover two further accounts in the Gospels of Matthew and Luke.

[...]

Four features in this story are without basis in the Gospels. The date of Christmas on December 25 does not appear until AD334 when in a Roman church calendar the Nativity of the Lord replaces the pagan feast of the Unvanquished Sun. Before the 4th century, the birth of Jesus was celebrated on January 6 (Epiphany), or April 21 or May 20.

The idea that Joseph was an old widower with a grown-up family comes from the apocryphal Protoevangelium of James, written in the 2nd century in an attempt to make less puzzling the by then current doctrine of the perpetual virginity of Mary and the gospel references to brothers and sisters of Jesus. The presence of an ox and an ass in the stable is also alien to the New Testament.

As for the kings or wise men, they were neither. Matthew calls them magi, magicians or stargazers, without mentioning their number. The figure of three is no doubt deduced from the reference to the gifts left by them: gold, frankincense and myrrh.

[...]

He also takes a critical look at the Gospel Nativity stories. Professor Vermes has e-mailed to say that he is not responsible for the article's title. He will also be on the BBC program on the Dead Sea Scrolls, noted yesterday, and he has a new book out: The Nativity: History and Legend (Penguin). Reviews are coming out, but don't seem to have reached Google yet.

UPDATE (5 December): Some reviews are noted here.

UPDATE (23 December): Another review is noted here.