Lustre serves as a parallel distributed file-system that's popular with high-performance cluster computing, icluding super-computers. For those unfamiliar with Lustre, see its Wikipedia page or Lustre.org.
With the Linux 3.11 kernel, Lustre file-system client support has been added. Greg Kroah-Hartman notes though, "Unfortunatly, due to it not building properly on a wide variety of different architectures (this was production code???), it is currently disabled from the build so as to not annoy people."
Other than adding Lustre, there's a a new USB MTK Bluetooth driver, lots of Comedi patches, various clean-ups, and random other work for the staging area of the Linux kernel. More details on the staging changes for Linux 3.11 can be found via his pull request.
Greg also was quick to send off his USB pull request. On the USB side there's lots of gadget updates along with ChipIdea driver updates, a new host controller driver, serial driver fixes, and there's no longer a 255 usb-serial device limitation for the Linux kernel.