There are current 9 failing layout tests on the buildbot. The layout test output is available at <http://build.webkit.org/results/post-commit-powerpc-mac-os-x/3065/results.html>, and it shows that the differences are almost all of the form: +frame '<!--framePath //<!--frame0-->-->' scrolled to -2,-0 These frame logs were introduced in r15970, and the buildbot results indicate the tests have been failing since then.
This appears to have since been fixed.