This is more of a mental note to self (and something which I kept forgetting the correct syntax for, despite using it in the past)… How to add an additional claims-aware web application to an existing Sharepoint 2010 farm.

$ap=Get-SPTrustedIdentityTokenIssuer
$uri = new-object System.Uri(“https://www.mydomain.com“)
$ap.ProviderRealms.Add($uri, “urn:sharepoint:mydomain”)
$ap.Update()

The original post courtesy of Steve Peschka:

http://blogs.technet.com/b/speschka/archive/2010/04/27/how-to-create-multiple-claims-auth-web-apps-in-a-single-sharepoint-2010-farm.aspx