I've been following a mish-mash of Google News alerts as well as some 'security' influencers on Twitter, but have a feeling there's a more efficient way to deal with this out there...
If you want to keep yourself about the latest discovered security vulnerabilities, BugTraq would probably be your best bet.
If you want to keep track of security breaches of organisations, the news would be your best bet. There is no consolidated resources that provide immediate feedback about such matters that I know of.
If you are looking for the vulnerability reports and databases, I've already answered this in this stackoverflow answer.
Copy-pasting again for easy reference:
Various list above have feeds or subscription feature which you can subscribe to get the vulnerability information delivered right to your inbox.