Retrieves all AD Groups used for permissions recursively within SharePoint

Get-SHPActiveDirectoryGroups.ps1

[System.Reflection.Assembly]::LoadWithPartialName("Microsoft.SharePoint")
$siteCollection = New-Object Microsoft.SharePoint.SPSite("http://companyweb")

foreach ($site in $siteCollection.AllWebs)
{
	foreach ($role in $($site.Roles))
	{
		foreach ($user in $role.Users)
		{
    		if ($($user.IsDomainGroup) -eq $True)
			{
				Write-Output $user.LoginName
			}
		}
	}
}