NO, if you are running on 1.0 you will get notification about the new update Once you click on it, that will download the file ( 93 MB ) and will install the new one, that is how I did it in my Dev Keon.

I see one more update now, its a 95 MB system update don't know what it is i am running Firefox OS 1.1

Strange, "Check for Updates" on 1.0.1.0-prerelease still reports: This is alread the latest version of Firefox OS

Perhaps it's a regional thing? I'm located in Germany.

Check for updates on the Geeksphones has been iffy, not all phones get the update. You are probably better off just manually updating.

Updating manually did the trick. Of course, all my user data was wiped, but that's OK. It's a developer device, after all.

I want to add: After updating manually, it seems necessary to ignore update notices on the device. With version 1.1, I got an update notice on the phone, and after following it, it came again, and then again, etc. With version 1.2, I also got an update notice on the phone, and after following it, I was back at version 1.1.