I am infinitely excited about this project! Thanks to Rebar Group for the incredibly interesting links and information! Anyways...
Here are some little tidbits I think may add to the collective mind-set:
Txtual Healing (which I believe is involved in the Drip Writing that Barrett linked to):
My favorite projects here are interactive...the artist sets up a projector which displays an image on a public wall (speech bubbles, recently an Obama poster) and invites passers-by to SMS text to fill in the blanks provided...
Petuel Park in Munich: a park which incorporates the work of 13 invidual artists. It reminds me almost of the Parc de la Villette in that many of the art pieces were designed for specific purposes, but when I visited I didn't see many people using them. Either way, these permanent and interactive pieces are interesting!
The Musical Folly is a piece with immovable chairs, all facing different directions, placed inside a wall of hedges from which music plays once a day. It's meant to be interactive, but doesn't leave much to interpretation by the visitor.
I don't know if this counts as a permanent flexible infrastructure...but it certainly creates an open-ended spacial experience: this public building in Munich uses images on the glass walls to create the effect an oversize curtain exposing balloons, and large books. Even the shadows of trees are an illusion.