One simple way to tell if a site is vulnerable is use one of the two links below:
http://rehmann.co/projects/heartbeat or http://filippo.io/Heartbleed/

Here are two sites that provide detailed information on the heartbeat SSL vulnerability: http://arstechnica.com/security/2014/04/critical-crypto-bug-in-openssl-opens-two-thirds-of-the-web-to-eavesdropping/ http://www.troyhunt.com/2014/04/everything-you-need-to-know-about.html