In English – for my non-technical readers – that means that you won’t notice a change in using the computer.
Convention over Configuration means that programmers get to do less work behind the scenes. This particular post was inspired by a recent Web Camp at Microsoft. “Convention over configuration” — direct from the lips of Rachel Appel — isn’t unique to Microsoft, but they worked it into the .NET framework in some kind of cool, geeky way.
In this case, names and locations of standardized files and folders have a convention. Rather than writing the equivalent of a new map for every time you need to create an application, you have an existing map that you re-use behind the scenes. Additionally, the painful process of telling the computer where everything is has been streamlined behind the scenes.  This resulted in the crazy ability to write some lines of code and have a computer create a database for you.