content: Article sums it up fairly well: an independent security researching team was approached by the FBI and offered a sum of money to disclose an iPhone software exploit that enabled them to create a hardware bypass to the PIN attempt tracker. As to the term "Gray-hat", the article also elaborates. Gray as in the literal middle between black and white. White hat hackers publicly disclose their findings in hopes of improving security. Black hat hackers do not disclose their findings in hopes of profiting from them exclusively. Grey hat hackers tend to disclose their findings, but typically only to governments or corporations and usually if the price is right.