While preparing a presentation for a customer I stumbled upon a nice blogpost the Agile Admin. The agile admin is written by Ernest Mueller, James Wickett, Karthik Gaekwad, and Peco Karayanev. The post presents a definition of DevOps, and I think I had the same in mind.
DevOps is the practice of operations and development engineers participating together in the entire service lifecycle, from design through the development process to production support.
Read the post and the comments for more background information