Oddly enough, it appears to be a different American AQ type, not the famous one.
U.S.-Born al Qaeda Arrest News Incorrect
Confusion Over Militant's Identity Sparked Reports of Gadahn Arrest; Some Media Say It is Another U.S.-Born Terrorist
Earlier it was reported by Pakistani media that intelligence agents had arrested Adam Gadahn, the American-born spokesman for al Qaeda, in an operation in the southern city of Karachi.
It was further reported by the Associated Press and Reuters that Gadahn had been arrested, sourcing security officials.
CBS News was told by sources in the Pakistan government that it was Gadahn, even after U.S. officials refused to confirm it was the California native for whom a $1 million reward has been posted.
Now, CBS News' Farhan Bokhari in Islamabad writes that earlier reports the detained individual was Gadahn proved false. According to a Pakistan security official who spoke with CBS News on condition of anonymity, the arrested individual is in fact "a Taliban militant leader who is known as Abu Yahya."
...
"In the light of our latest information, I can say, this is not looking like Gadahn. But it is still the arrest of an important Taliban militant," said the Pakistani security official who spoke to CBS News late Sunday.
The New York Times, sourcing American and Pakistani officials, reports that the man arrested was Abu Yahya Mujahdeen Al-Adam, and describes him as an al Qaeda commander who was born in Pennsylvania.
http://www.cbsnews.com/stories/2010/03/07/world/main6275953.shtml
Added on edit: as of 8:48 ET CNN is still leading with the arrest and pictures of Gadahn. (While noting it's not confirmed by the US)