@PearlRiver: Good tip. I notice that the View menu also shows a keyboard shortcut, <option><command><T>, that toggles between "show" Safari toolbar and Hide Safari Toolbar. This is on my Mac OS X 10.7.5 running Safari 6.0.5.
However, there are some inconsistencies with this: <option><command><T> does not work in Full Screen mode. But you can toggle Full Screen mode Off/On either using <Ctrl><Cmd><F>, or by holding the cursor's hot spot (tip of the arrow cursor) at the top edge of the display, until the Finder's Menu Bar pops down again.
IMO, Apple has lost its grip. There are now so many undocumented and seriously puzzling GUI behaviours in our once-beloved Mac OS X, that I am half seriously looking for a welll thought out, consistent replacement. I suspect things are only going to get worse with OS X Mavericks, with the move to put the same, gesture-driven interface on both OS X and IOS 7. IMO, the sanguine thing to do is for Apple to provide OS X Mavericks with a simple "Toggle" between the IOS GUI and the original Mac OS X GUI. This would work better for gesture-challenged people like me. I am one of those who detest the IOS GUI and seriously handicapped, and occasionally just plain wrong, spelling-prediction on my iPhone (and Macs), But then I also prefer a real, physical QWERTY keyboard. I am part of the dying breed of literate dinosaurs.