One huge oversight in Windows 8 Chrome is the lack of pinch-to-zoom support. This is standard functionality that should come with any touchscreen-enabled app. Google is aiming to correct this with the latest Chrome Canary update for Windows.
The feature has been automatically activated for anyone using Chrome Canary for Windows 8 or above. This will work in both Metro and Desktop.
It should be only a matter of time before this improvement comes to Chrome Beta, and later Chrome Stable Channel. Chrome Canary is pretty much an alpha product. Canary gets all the upgrades first, but sacrifices stability many times. You will find bugs and other issues, so those who are not comfortable with that should avoid Canary.
With that said, you can go ahead and download Chrome Canary straight from Google, or just wait to get the update in other channels.