A universal proof checker called Dedukti has been realeased. This is an implementation of a type checker for proofs written in the -modulo calculus.
To make the translator useful in practice, we are currently writting different translator from already existing proof assistants to Dedukti . Our effort are now concentrated on the translation from Coq. This raised difficult theoretical questions that are under investigation.
Dedukti is available from ULR http://www.lix.polytechnique.fr/dedukti . It is written in Haskell and is short enough to be trustable. It is a product of a long run collaboration with other INRIA teams. This collaboration was formalized by an INRIA ARC (special funding for collaborated INRIA teams).