The "Heartbleed Bug" has been in the news a lot lately, and for good reason. It's a security vulnerability in some versions of OpenSSL that allows the theft of information that is protected, under normal conditions, by the SSL/TLS encryption used to secure the Internet. It's estimated that this has impacted about 30% of all websites. That's a lot of websites.
The good news for PharmGKB users is that our services were not affected by the bug. You do not have to change your password on PharmGKB.
If you're looking for a simple explanation of the problem, xkcd has the most concise one I've seen to date: