I might gloss the term, but I would not translate "association de préfiguration" when it's part of the title of the association:
A Pre-Launch Association (Association de préfiguration de la Maison de l'histoire de France) is implementing the Committee's recommendations and preparing to create the future public institution (établissement public) which will come into being on 1st January 2012.
http://www.maison-histoire.fr/wp-content/uploads/2011/11/kit...

Here are some more examples:
About the Author
Thierry de Duve is Director of Studies, Association de préfiguration de l'Ecole des Beaux-Arts de la Ville de Paris.

About the Editor
Thierry de Duve is Director of Studies, Association de préfiguration de l'Ecole des Beaux-Arts de la Ville de Paris.
http://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid...

--------------------------------------------------
Note added at 39 mins (2012-01-25 14:07:46 GMT)
--------------------------------------------------

Sorry, missing URL:
About the Author
Thierry de Duve is Director of Studies, Association de préfiguration de l'Ecole des Beaux-Arts de la Ville de Paris.
http://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid...

But since Thierry de Duve is the subject of the last two examples, here's another:
ADPIOS (Association de Préfiguration de l’Internet of Subjects) is an independent, non-profit European professional association working towards making the Internet a trustworthy place where individuals and organizations can exist as autonomous entities.
http://www.sosnetwork.eu/about/partners

the committee has also established a temporary association, “Association de préfiguration du réseau européen d’histoire de l’architecture” that organizes the discussion and vote of the members.
http://www.eahn.org/site/en/descriptionandhistory.php

The Director of the Centre Pompidou-Metz is Laurent Le Bon, Curator-in-Chief of the National Museum of Modern Art and currently Director of the interim body, the Association de Préfiguration du Centre Pompidou-Metz.
http://www.claudinecolin.com/en/archives-513-opening-of-the-...

There are many more similar references. Some (as above) have glossed "préfiguration" as "pre-launch" or "temporary" or "interim." ;-)

--------------------------------------------------
Note added at 44 mins (2012-01-25 14:12:33 GMT)
--------------------------------------------------

Hi Paul, I only just saw your Note. If not in being used as part of the title of an organization, I think I'd go with interim (or temporary) organization. ;-)