Regression in 3.0pre With content_for And Layouts

I just found a regression in a recent commit in the trunk for 3.0 that involves using content_for to help get content in both templates and layouts, a technique described one of Ryan's earliest screen casts. My patch adds a regression test that passes before said commit but is not quite yet in full parity with rails 2.3.4. Could someone please take a look at this and give me some feedback on what else I might be able to do to get these features back?