I noticed that some of my latest test images using the 10.7.4 combo update in the vanilla catalog would report the need to install a 10.7.4 Supplementary Update upon running Software Update. Seeing no such package available for separate download on Apple’s site, I went back to the combo updater page and tried downloading again via InstaUp2Date. Lo and behold, the checksum is now different. So for now, you may want to manually substitute the following line in the 10.7-vanilla catalog:
MacOSXUpdCombo10.7.4 http://support.apple.com/downloads/DL1524/en_US/MacOSXUpdCombo10.7.4.dmg sha1:b11d511a50d9b728532688768fcdee9c1930037f