If you’re a regular Chromebook user and worried about the Meltdown bug endangering your data, Google has published a table on the Chromium Wiki detailing which devices are vulnerable, which aren’t, and which have been patched. You can read it in full here.
If the table says “Yes” or “Not needed” in the column labelled “CVE-2017-5754 mitigations (KPTI) on M63?” then the device is safe. If it says “no,” then it’ll need an update to make things right. And if it says “EoL” (meaning “end-of-life”) then that update is never coming because the device is no longer supported.
The list (seen via AndroidPolice) shows what we already knew — that most of Google’s own devices are already protected. Meltdown affects mainly Intel processors (although some ARM chips are vulnerable too) and Intel-based Chromebooks are safe if they use versions 3.18 or 4.4 of the Linux kernel. You can check this on your own Chrome OS device by going to “chrome://gpu” then looking at the “Operating System” row in the table marked “Version Information.”
Protecting individual devices against Meltdown (and its sister-bug Spectre) is only part of the battle. These are fundamental flaws that have been exposed in the very architecture of the world’s most popular processors. And these problems aren’t going to go away quickly.