There is an article of interest by Josep Rius-Camps in the latest issue of NTS 53 (2007): 379-405: "The Pericope of the Adulteress Reconsidered: The Nomadic Misfortunes of a Bold Pericope."
"This article considers afresh the origin of the pericope of the adulteress, which is absent from some important manuscripts. Comparison of the witnesses to the text reveals that it has been preserved in two distinct forms, one (attested by Codex Bezae and the minuscules 2722 and 1071) that is Markan in style, and the other (attested by f13) that reproduces the style of Luke. The conclusion drawn is that the account was first composed by Mark (and placed after Mark 12.12) and subsequently adopted by Luke (after Luke 20.19). Because of the apparent moral leniency displayed by Jesus, the story would have been removed at an early date from both Gospels, and then later reinserted by some manuscripts but at different places."