Apple just rolled out the Safari 3.1.1 bugfix and security update. As far as we can see, it still asks Windows users to install Safari even if they don't already have Safari installed. Update: We just tried this again, just to be sure, on a completely virgin computer with neither iTunes or Safari installed.
After installing iTunes and updating Apple Software Update to 2.1, it gave us the image above. The checkbox is still checked by default, BUT the difference now is that it's under "New Software" instead of "Updates". A distinction that should make it more clear that you're installing a new piece of software instead of updating something you've already installed previously. [Apple]