MS Software Update Service-Reboot Issue

I read through a white paper on SUS, and my opinion on this is, unfortunately, no.
Some hotfixes require a reboot to remove a replaced file from memory. For example, WINLOGON.EXE is always running (in RAM) when your Windows clients are on. When a hotfix replaces WINLOGON.EXE, the file is overwritten in the WINNT\SYSTEM32 directory, but the "copy" active in RAM is NOT replaced. You have to reboot to clear this file from memory.

Now, some hotfixes do not require a reboot, since the files are not active at that time.

Therefore, I would set up your hotfix rollouts to run once a week, at the middle of the night (say, Saturday at 3AM), and make your users know that they had better log off when they leave on Saturday, due to SUS. Tell them that patches are applied Saturdays at 3AM, and that their machine will be rebooted during the process for the patch to take effect.
Then, when a user does NOT log off Friday night, and they come in Monday morning and their system was rebooted (and say they had a Word doc open but unsaved, so they lost the document) you can tell them that IT policy has it that users MUST log off on Fridays for software patching. Any work lost is NOT the fault of the IT dept if the user does not follow the guildlines!

Get tough on your users. They will learn.