Extract Details about your Site Links

Import-Module ActiveDirectory 
$ConfigPath = (Get-ADRootDSE).configurationNamingContext           
Get-ADObject -Filter 'ObjectClass -eq "siteLink"' -SearchBase $ConfigPath -Properties * | Format-Table Name, replInterval, cost, siteList -AutoSize    


From:
http://blogs.technet.com/b/ashleymcglone/archive/2010/10/06/powershell-to-automatically-create-all-ad-hub-to-spoke-site-links.aspx

Bonus Link
http://blogs.technet.com/b/ashleymcglone/archive/2011/06/29/report-and-edit-ad-site-links-from-powershell-turbo-your-ad-replication.aspx