While many news outlets were blathering on about the end of life for Windows XP, a huge hole in OpenSSL was discovered. OpenSSL secures a huge percentage of the Internet, meaning many of the sites you use have had their security compromised.
These revelations, while painful, are very much necessary to create a more secure Internet.
The Heartbleed Bug is a serious vulnerability in the popular OpenSSL cryptographic software library. This weakness allows stealing the information protected, under normal conditions, by the SSL/TLS encryption used to secure the Internet. SSL/TLS provides communication security and privacy over the Internet for applications such as web, email, instant messaging IM and some virtual private networks VPNs.The Heartbleed bug allows anyone on the Internet to read the memory of the systems protected by the vulnerable versions of the OpenSSL software. This compromises the secret keys used to identify the service providers and to encrypt the traffic, the names and passwords of the users and the actual content. This allows attackers to eavesdrop on communications, steal data directly from the services and users and to impersonate services and users.
via Heartbleed Bug.
Bonus link: Bruce Schneier on the Heartbleed bug.