Safari 4 will continue the "we don't adhere" mantra...
Apparently, Apple simply doesn't care about their own UI guidelines when it comes to iLife apps and Safari. The newest offender is of course Safari 4's "tab bar inside the window titlebar". It's very inconsistent, and sadly, you can only grab tabs from the top right corner of each tab. Grabbing the title, as before, will result in moving the whole window. Many people tend to arrange their windows. Me personally, for example, I like my windows to be hooked top-left. A couple of pixels below the menubar and to the right of the left display edge. Grabbing the tabs at the wrong place results in me constantly having to put the window back where it belongs.
Of course, you can solve the problem by typing "defaults write com.apple.Safari DebugSafari4TabBarIsOnTop -bool NO" without the quotes into a Terminal window and hitting return after that. Restarting Safari will then show you tabs the old way. (Do the same with "YES" to restore the new default-functionality.) But I don't want to have to hack my systems whenever I set them up. Nowadays, I have to restore a 2D dock via such a command, and now I have to restore a decent tabbing behaviour to Safari. Of course I also have to install LaunchBar and other utilities, but that's something I've come to terms with since, I guess, around Mac OS X 10.1. But to me, a couple of tabs in the window titlebar of Safari just looks kinda messy. I find the old way more logical.
Of course the new way reduces the vertical footprint of Safari windows, which could mean good things for a netbook. (Hint?)