Bumped into the topic of pattern language on Merlin Mann's 43 Folders (see favorite links). Further search linked me to the original book site and this nice summary quote about the concept.
"Normally what happens when you build a house, for example, is that an architect, tries more or less or understand what you want and makes a blueprint. But a blueprint and CAD designs are mostly guess work about what is going to be just right for the dimension of a room or the placement of a window. It's like tossing thirty coins all at once and hoping they all land on heads. Never works. A sequence is figuring out which decision has to come first and getting it right and then moving to a second decision. Like tossing one coin at a time, which is actually a much better, faster, and less expensive way to get to thirty coins all on heads. But if you work from a blueprint you are stuck with your guesses and the builders, who aren't the architect, just have to follow the blueprint, even when they know a much better solution. It's a silly way to do things." SOURCE
The link below, which Merlin references, takes "pattern language" out of its architectural source and applies it to projects generally and to personal productivity. The general idea seems to be to stress process and to avoid defining product or outcome prematurely. One step at a time. LINK
