Steven Johnson has a blog entry about the virtues of short blocks and how they might be a metaphor for the blogosphere, picking up on his excellent talk at the O'Reilly Emerging Tech Conference 2002. This sent me scurrying to my copy of the wonderful A Pattern Language by Christopher Alexander to see if there were any related patterns. The closest is no. 61 Small Public Squares. This has some interesting discussion of sizes of squares and pedestrian density.