Check out this line to determine when an installation required a system restart:
Get-EventLog -InstanceId 1038 -LogName Application | ForEach-Object { $i=1|Select-Object Date,Product,Version,Company;` $i.Date = $_.TimeWritten $i.Product,$i.Version,` $i.Company = $_.ReplacementStrings[0,1,5] $i }
It will return an exception if no such events are found. Otherwise, you will get a listing with the dates and the products that required a system restart.
