Google has posted the factory images for Android 4.4.4 Release 2 — but only for a few specific carriers in a few select countries. And only for the Nexus 5. The release, which carries a build number of KTU84Q, is available for download from Google's Android factory images page, is only good for the Nexus 5 on Telstra in Australia, 2Degrees in New Zealand, and unlocked in India.
There's no word of what's included in 4.4.4 Release 2, but we know that there's some tweaks to address carrier-specific radio needs (hence the limited release) and maybe a few bug fixes.
Look for an over-the-air update imminently. But if you happen to have a compatible Nexus 5 and just have to have Android 4.4.4 Release 2 installed right the heck now, well, that is something you can do.
You can grab both the factory image (again, only bother with this if you're on the right carrier in the correct region) at the source link below, and get instructions for installation in our definitive Nexus updating guide.