This is a good thing but there is a possible crisis coming. For some, May 5th may be the end of the online world. It depends. Let me tell you the story. While I'm at it, I'll help our competition along the way who missed a few salient points.
In short, all Internet-facing servers have a unique IP address and it is DNS which translates the friendly names we know into those addresses. Consider DNS the wise old sage of the Internet who has everyone in his rolodex.
Yet, not everyone on the Internet is as nice as you and I. There are people who would like to intercept DNS requests - imagine if (for instance) your online banking transactions were actually sent to a hostile phishing server, because the DNS request was intercepted and tampered with?
DNSSEC is the next generation of DNS; fundamentally it stands for DNS Security Extensions and, as you might gather, adds security to the DNS protocol.
DNSSEC is designed to protect the Internet from attacks like the one described above, otherwise known as 'man in the middle'.
There are other DNS vulnerabilities like cache poisoning. In this scenario, the bad guys aren't just intercepting one request and sending you elsewhere. Instead, they are seeking to inject bad data into your DNS cache which can affect future DNS lookups made.