Some developers claim it's getting out of hand, since there are now 4 different installations of Chrome, which include Stable, Beta, Dev and now Canary. Canary is basically the Dev version, with more often updates, generally coming from the nightly builds. For obvious reasons this should not be your default browser, which is why that option has been disabled in this build. This version of the browser is likely to crash very often, due to the fact they will update it almost daily direct from the fresh testing code.
I have Canary installed and it is almost identical to the Dev which I have always been running since I started using chrome last year. They work seamlessly together, and I rather like the all yellow logo they have for this build. I now plan to move to the Beta channel of Chrome, as this is more stable. This way I can see all the new features, and test new web applications using the Canary build, so I find this very useful, thanks Google!
You can Download Google Canary from here.