Find last boot time
When did we last reboot this machine? What's the current uptime? How long since boot, since reboot, since last boot, since last reboot?
In powershell 2:
Get-WmiObject win32_operatingsystem | select csname, @{LABEL='LastBootUpTime';EXPRESSION={$_.ConverttoDateTime($_.lastbootuptime)}}
In Powershell 3+
Get-CimInstance -ClassName win32_operatingsystem | select csname, lastbootuptime