Unless I'm misremembering, unless you ask for detailed information about the updates, it doesn't tell you ahead of time if it's going to ask to restart your computer. It just says basically, "There are updates available. Do you want them?"
you're probably misremembering -- there's a little arrow next to the update items which require a reboot, and even after installing everything, you can still choose to reboot later. I still have a system running Tiger so I don't think it's changed since then.
I just checked. The standard Software Update screen in 10.6 doesn't have a list of items. It just has three buttons: "Show Details", "Not Now" and "Install" — the list you're talking about is revealed by "Show Details." You do still have the option to wait as long as you want to restart, though.
