The irony is that most geeks don't hold huge significance to their nicks. So if you're a reporter, don't bother asking geeks about their nicks. It usually wastes both of our time. This is a shorthand expression that refers to one of the core debates in the Free Software and Open Source movement. The other half is easy to understand for cheapskates.
Beer costs money.
The other aspect to this is the subtle difference between the Open Source Initiative and The Free Software Foundation. OSI believes that software can be developed better if it is done in the open. The FSF believes that it is ethically wrong for software to be closed. This is, of course, an oversimplification, but you get the idea. The zealots are pretty loud on all of these points, and understanding them is critical to understanding many of the central debates on Slashdot.