Following these instructions you can add an LED matrix to almost any piece of clothing. The whole display can be controlled using one output for each vertical and horizontal thread. The first step is to solder crimping beads onto each surface mount LED you will be using. Next sew a grid of conductive thread into your garment keeping the vertical and horizontal threads on opposite sides of the fabric. Each of these threads is terminated at a sewn on microcontroller socket. The LEDs are sewn on at each thread junction. She doesn't have any code posted yet unfortunately, but there is an example movie of Conway's Game of Life.

[thanks lobo]