Get all logged on users

#Init report array
$report = @()

#Server name array
$servers = 'serverA','serverB'

#Collect explorer info
$users = invoke-command -computername $servers -scriptBlock {Get-WMIObject Win32_Process -filter 'name="explorer.exe"' | foreach { $_.GetOwner() } | sort user -unique}

foreach ($u in $users)
    {
    $userData = "" | select name,server
    $userData.name = $u.user
    $userData.Server = $u.PSComputerName
    $report += $userData
    }

$report | sort server | format-table -auto