No disclosureIf you click Next without changing the default option, you tacitly agree to install Apple Software Update. You then see another installer dialog box, shown here. The link at the bottom of this dialog box says the software is subject to the original license agreement and points to the Apple - Legal web page. As of March 24, 2008, this page does not include the text of the Apple Software Update license agreement.
For the full story, see What Microsoft can teach Apple about software updates