I upgraded ember-data two days ago to the latest version and bumped into the same thing. I had to upgrade ember.js, too, to have the new promises API. I used the first commit that introduced it.
This is the header of my ember.js file:
// Version: v1.0.0-rc.3-74-gffad8ef
// Last commit: ffad8ef (2013-04-25 17:12:00 -0700)
And that of the ember-data.js file:
// Last commit: 308b13e (2013-04-29 09:29:13 -0700)
You can find builds of both ember.js and ember-data.js at builds.emberjs.com.
The upgrade path was not smooth after that but was not particularly bumpy, either. I had to handle the issues covered in
Hope this helps.