Unfortunately, there was a second regression in 1.1 that didn't get caught in time to make it into 1.1.1. On that account 1.1.2 is out now to correct that issue. For more information about the problem see Issue #3637.
We recommend that everyone using 1.1.0 and 1.1.1 upgrade at their nearest convenience. Head on over to emberjs.com/builds to download. Our apologies for the inconvenience.
Ember 1.2 Beta 2
While we were at it, we also released the second 1.2 beta which includes a couple of bug fixes. 1.2.0-beta.2 is also available at emberjs.com/builds.