We don't have a report for this. View > Deployment Tracker should tell you if a reboot is needed, something like this: (show failures only in the view)
We do have an ITScript 'Get Reboot Time' that would tell you the last time the machine was rebooted. You would need the ITScripts feature enabled. You can verify this from Help > About.
Alright! even notification does not have, right?
Maybe we will be using that kind of monitoring instead. Since this is critical when deploying new patches on target machine and this machine not rebooted in the last patch installed.