They've dubbed the issue Heartbleed and it affects servers that have a vulnerable implementation of OpenSSL. Please read through this particular link about affected sites and passwords that you should be changing as soon as you can: Mashable.
For more information about Heartbleed, go here: heartbleed.com
For more information about Heartbleed, go here: heartbleed.com
Woof,
Ruckus the Eskie