According to ESPN, testing by the California State Department of Justice has confirmed that there was indeed plaster of paris in Antonio Margarito's wraps.
A California Department of Justice senior criminalist who inspected the wrappings under a stereomicroscope and with an X-ray fluorescence spectrometer determined the wraps contained sulfur and calcium, according to a document obtained by the Times. Those two elements, with the addition of oxygen, make plaster of Paris.
The hand wraps were removed from Margarito's fists shortly before his Jan. 24 title fight against Mosley when Mosley's trainer, Nazim Richardson, objected to their use. The hardened gauze pads, which had been inserted inside the hand wraps near Margarito's knuckles, were seized by the California State Athletic Commission, which sanctions and oversees boxing in the state.
In addition, the article mentions that Margarito and Capetillo have not appealed their suspensions. Bob Arum finally shut up about the matter, saying that he had no comment.
Personally, I really hope the California State Athletic Commission really throws the book at Margarito and Capetillo, and I hope Margarito gets charged with attempted aggrevated battery. There's absolutely no place for this kind of cheating in boxing. This type of unfair advantage can lead to serious damage or even death. Just ask Billy Collins' parents.