The 2014 releases of the Moto X and Moto G have been available for a few weeks, but for some reason Motorola has been a bit slow to release the usual mandatory kernel source code. Today you can find them both on Motorola's development GitHub, confirmed by a Motorola employee in the comment section of the wider MSM kernel. Get after it, ROM cookers.
If you've never read one of these posts before, the kernel is the Linux-based baseline software that runs underneath Android and allows it to interact with phone or tablet hardware. The one that Android uses is based on open source software, so manufacturers are required to publish the source code publicly for others to inspect and, if they wish, modify. Those who like messing with hardware tweaks or loading up new ROMs with customized features appreciate this, though a phone usually needs an unlocked bootloader in order for a custom kernel to be flashed. Sorry, AT&T and Verizon users.
Motorola is offering the initial kernels for the Moto X 2014 (codenamed "Victara") and the Moto G 2014 (codenamed "Titan") as both a standard browsable Github and a downloadable ZIP or TAR file. Check the source below for the individual links. Motorola should post updated versions if and when new software is released, and the Android 5.0 update will certainly need a new kernel.