In his presentation at RT3 on January 11, Nicolas Bourriaud has been referring to a series of texts by Louis Althusser that are introducing the concept of "aleatory materialism". Written between 1982 and 1986 and published posthumous these short texts seem widely unkown today - at least outside of the french and italian (post-)marxist circles. Here are a few links to interesting sources:

Wal Suchting: Althusser"s Late Thinking About Materialism
http://www.generation-online.org/p/suchting_althusser.pdf

A major subject of reflection in this second phase was materialism – "one of the most sensitive subjects [thèmes névralgiques] in philosophy", "the hardest question of all". Very roughly speaking, his work here falls into two periods. The first is marked most nota bly by his lecture "The Transformation of Philosophy" (1976). During the second, from about mid-1982 to mid-1986, he produced a number of pieces which sought to delineate a certain "unique tradition" of materialism, an "underground current", a "materialist tradition almost completely ignored in the history of philosophy", which was not present (explicitly anyway) in his earlier writings. This he called both the "materia lism of the encounter [matérialisme de la rencontre]" and "aleatory materialism" (by which latter name it will be referred to from now on). Only a small part of this was publicly accessible during his lifetime, and not all of it has been published since his death. However, it seems fairly clear that, at the very least, enough of it is now in print to permit a study of its main lines. This will be the main task of the present paper.

Augusto Illuminati: Recent Italian Translations of Althusser's Texts
on Aleatory Materialism
http://www.borderlandsejournal.adelaide.edu.au/vol4no2_2005/illuminati_t...

A review of the italian translations of Althussers texts on aleatory materielism for the issue on Althusser of australian journal "borderlands": http://www.borderlandsejournal.adelaide.edu.au/issues/vol4no2.html

Dunja Larise: The Aleatoric Materialism. L. Althussers" Late Theoretic Project
http://hrcak.srce.hr/file/9121 (PDF of the text in german)

In a time interval of four years, from 1982 to 1986, Louis Althusser wrote a number of short papers, which were all published posthumous. Short papers are typical for Althusser"s work, much more than every other art of writings, but the main characteristic of his last papers lies neither in their form nor in the method – it lies rather in a radically new approach to the politics. During the sixties, Althusser holds a point of view according to which the dialectical materialism represents the philosophical core of the Marxism and the historical materialism corresponds to its science. In the eighties, he changes this theoretical approach in favour of a “philosophy of the encounter”, which in his opinion reflects the non-teleological principle of materialism in far more exact way, than the dialectical materialism which becomes logocentric and idealistic. Dialectical materialism will be completely rejected, and a new term will step into its place: the aleatoric materialism, a materialism of contingency and emptiness that radically rejects any precedence of the sense over the phenomena. The following text pursues this radical late turn in Althusserian understanding of philosophy, primarily in its relation to politics and ideology.