Display SharePoint 2007/2010 Site Collection Administrators

#SP_Display-SiteCollectionAdmins1.ps1 -URL <string>
#
#Author: SharePoint
#Last Modified Date: Mar. 25, 2011
#
#Display all site collection admins for all site collections
# within a web application.
###########################################################

[void][System.Reflection.Assembly]::LoadWithPartialName('Microsoft.SharePoint')

#DECLARE VARIABLES
[string]$siteUrl = $args[0]

function GetMissingParameter
{
  $script:siteUrl = Read-Host "Enter Site URL"
}

############
# MAIN
############

#IF MISSING PARM FOR SITE URL, ASK FOR INPUT TO FILL
if($args.length -eq 0)
{
  GetMissingParameter
}

$rootSite = New-Object Microsoft.SharePoint.SPSite($siteUrl)
$spWebApp = $rootSite.WebApplication

foreach($site in $spWebApp.Sites)
{
    foreach($siteAdmin in $site.RootWeb.SiteAdministrators)
    {
        Write-Host "$($siteAdmin.ParentWeb.Url) - $($siteAdmin.DisplayName)"
    }
    
    $site.Dispose()
}
$rootSite.Dispose()