I have a D70, and can tell you that unfortunately it doesn't. You have to use Nikon's tool (or the Photoshop CS plugin) to convert them to something else.
Now, iPhoto does SEE the raw files, and will pull them over - but what it seems to be grabbing is an encapsulated thumbnail. You get a tiny little image, that's all.
It'd be great if someone could develop a plugin for iPhoto though...