From the webpage:
Disco is powerful and easy to use, thanks to Python. Disco distributes and replicates your data, and schedules your jobs efficiently. Disco even includes the tools you need to index billions of data points and query them in real-time.
I rather like the MapReduce graphic you will see at About.
I first saw this in Guido Kollerie’s post on the recent Python users meeting in the Netherlands. Guido details his 5 minute presentation on Disco.