Canary builds is a new Google Chrome channel aimed at early adopters and developers: which unlike the beta and dev channel, "can be installed without overwriting regular Chrome build"….meaning you can install both Canary and regular build (stable/beta/dev).
Canary build available for Windows, is "installed to a different path, gets updated separately, and runs side by side with an existing stable/beta/dev installation". Google says that Canary build will usually be the same as dev. "Sometimes if necessary, we may push additional updates on Canary build so its version is higher than dev."
If you're doing development/test for chromium project or interesting in getting involved, it's recommend you install canary build and use it on daily basis. It helps you keep track of activities from both trunk and release branches.
Download: Canary Build