Just looked at the update. "we have migrated Cryptocat's network into new servers inside a Swedish nuclear bunker" Holy Crap!
https://blog.crypto.cat/wp-content/uploads/2013/02/Port_sn_0...
The main crypto.cat page loads fine over HTTPS (certificate has sha1 thumbprint d1aa1c1037202e359f224e407d7f84a0e8a94dd7 which i see is advertised on the erroring blog.crypto.cat page).
Why has the certificate changed? Why did the CA signing the SSL certificate change? Is there any forwarding message signed by the original certificate?