It provides a basic infrastructure for function "live patching" (i.e. code redirection), including API for kernel modules containing the actual patches, and API/ABI for userspace to be able to operate on the patches (look up what patches are applied, enable/disable them, etc). It's relatively simple and minimalistic, as it's making use of existing kernel infrastructure (namely ftrace) as much as possible. It's also self-contained, in a sense that it doesn't hook itself in any other kernel subsystem (it doesn't even touch any other code). It's now implemented for x86 only as a reference architecture, but support for powerpc, s390 and arm is already in the works (adding arch-specific support basically boils down to teaching ftrace about regs-saving).
We loved it so much that we wanted to create something with them that felt Snapchat-y. So we built a Snapcash prototype and shared it with the team at Square. Luckily for us, they were just as excited as we were and wanted to build it together.
The difficult we do today; the impossible takes a little longer.