Two months after the Raspberry Pi default firmware upgraded to Linux 4.0, they've now upgraded to Linux 4.1 as the latest stable kernel.

Linux 4.1 brings many new features and improvements and is now served as the kernel for the Pi's default firmware. The source had been available for a while already with some RPi-focused Linux distributions like OpenELEC already having opted to utilize it for the newest Linux kernel capabilities.

More details on the kernel upgrade via this RaspberryPi.org forum thread.