Seems like it. I just typed "vim" at a Terminal prompt in Leopard and was greeted with VIM 7.0.234.
I certainly didn't install that myself -- I use emacs on my local machines, although I admit I've been struggling to learn enough vi to do editing on remote servers.
I guess it's theoretically possible that vim came along with Xcode or MacPorts, but I can't imagine what I might have installed that had vim as a dependency.