http://www.thesmartset.com/article/article02011301.aspx

A number of points are attested to in favor of this theory:

1) Superman was created by Joe Shuster and Jerry Siegel, two Jewish boys from Cleveland.

2) Superman’s name on Krypton was “Kal-El," which means “Voice of God” in Hebrew.

3) Superman was sent to Earth as a baby by his parents to save him from destruction; he was adopted by people not his own. This was like Moses, sent out in his basket to escape death and plucked from the bulrushes by the Pharaoh’s daughter.

4) "Kent" could be an Americanization of "Cohen" — though I have to say that there are no Kents in my family.

5) Superman in his disguise as Clark Kent sought to assimilate into American life, much as Jewish immigrants of the time tried to do.

6) Clark Kent, with his studious demeanor and thick glasses was, let’s face it, the embodiment of a Jewish stereotype of the period.

7) The destruction of the planet Krypton can be taken as a metaphor for the destruction of European Jewry during World War II, occurring near the time that Siegel and Shuster launched the series.

8) Man is a popular suffix in a Jewish name. "Superman" has this suffix and can be pronounced to emphasize the fact — say Superman in the manner of Lieberman or Klingerman.

Norwich also pointed out the superhero’s continuing topicality: “We shouldn’t forget that he is an illegal alien.”