Linux 5.1 released after 13k code commits since 5.0
Linux 5.1 is now available with new hardware support, new ACPI support and support for HDCP 2.2 on Intel platforms as well as Spectre-related optimizations.
There's also Heterogeneous Memory Management for the Nouveau DRM driver which is, quite frankly, useless as long as NVidia is ensuring their cards are running as slow as possible with the Nouveau driver using signed firmware. On the CPU side of things there's support for the Bitmain SoC, a few new ARM SoCs and there is better RISC-V support.
Kernel 5.1 is, as usual, downloadable from kernel.org.
Linus Torvalds announcement is in the Linux Kernel Mailing List.