I downloaded the latest nightly tonight (Jan. 6th) on my intel powerbook (running OS X 10.5.6). When I go to run the acid 3 test, the browser crashes before it hits 100%. This hasn't happened with any of the previous builds. Here's a video of it: http://screencast.com/t/aH3woNFf
Please attach a crash log: <http://webkit.org/quality/crashlogs.html>.
I spotted the problem via code inspection. Fixed in r39671.