Here's the news: Thawte delivered the message about stopping it's free mail certification a week ago (by means of an an unsigned email).
The StartSSL root certificates are included in Windows since last month, as it was part of the root server update pushed to all client via Windows Update. The official source for this available here
The CA Cert one has not yet been approved and they are still in audit phase with Microsoft. The certificate can be manually imported with these instructions.