Story is in Velo-News. This is for bikes equipped with ten-cog cassettes.
"...PowerLocks stamped with “M” and “N” date codes are the targets of the recall. The date code letter is stamped onto the end of each PowerLock outer plate, near the pin. .."
"...SRAM noted that the safety issue (cracking of the outer plate) typically happens upon installation of the PowerLock or during first use..."
Anyway, go read the whole article if you have a bike with a SRAM chain on a 10 cog setup.