A Mac OS X Utility that enables the ability to change several hidden preferences in the Safari 4 Public Beta web browser, such as: moving the Tab Bar, reverting the Progress Style indicator, disabling Google Suggest and Top Sites and more.I think the tabs on top approach is intended to show the tabs open across multiple open Safari 4 windows without you having to click on the underneath windw, or they're simply copying Google's Chrome.
Terminal method to directly set preference:
To quickly change the tabs to the old Safari 3 position enter the following into terminal:
defaults write com.apple.Safari DebugSafari4TabBarIsOnTop -bool NO
To change tabs back to the top, enter again but with -bool YES at the end.