Yes, Senator Arlen Specter is a Jew.
His biography (excerpted from Wikipedia) echoes some familiar patterns among American Jews.
He was born in 1930 in Wichita, Kansas to parents Lillie Shanin and Harry Specter who emigrated from Russia in 1911. His father served in the US infantry during WWI, and was badly wounded. During the Depression, Specter's father was a fruit peddler, a tailor and junkyard owner. Specter worked with him, learning the importance of hard work at an early age.
Specter graduated Phi Beta Kappa from the University of Pennsylvania in 1951. He served in the United States Air Force from 1951 to 1953 during the Korean War. He graduated from Yale Law School in 1956.
He is married to the former Joan Levy, and they reside in the East Falls section of Philadelphia. They have two sons, Shanin and Stephen, and four grandchildren, Silvi, Perri, Lilli, and Hatti.
Spector has served with distinction in the senate as a Republican from Pennsylvania since 1981. He switched to the Democratic party on 4/28/2009 and will stand for reelection in 2010 - as a Democrat.