Essays on Derek Parfit's On What Matters, edited by Juissi Suikkanen and John Cottingham. This book is due out shortly in late October.
The Amazon description reads, aptly:
In Essays on Derek Parfit's On What Matters, seven leading moral philosophers offer critical evaluations of the central ideas presented in a greatly anticipated new work by world-renowned moral philosopher Derek Parfit.
An Amazon.com search, or for that matter a Google search, reveals no pending release date for On What Matters. Perhaps the editors have dabbled in the Newcomb problem? Or have they simply read too much David Lewis?
For the pointer I thank Alex T., a loyal MR blogger.