From the wikipedia article on BDD:
BDD is a second-generation, outside-in, pull-based, multiple-stakeholder, multiple-scale, high-automation, agile me
I wrote a blog post on where I learned about BDD as couple of weeks ago. It focus on the .NET platform toolwise and is a bit Cucumber heavy since I like it, but you can pick out some BDD/ATDD stuff from there as well.
When it comes to articles and books I second the suggestions above - it's starts there!
But you should also checkout:
Well - there you have it. My short list for things to read.