Although all we have to go on is his twitter announcement, Jimmy Bogard has put the project is up on CodePlex.  It is version 0.1, so prepare to bleed if you want to use it (bleeding edge), but this library tries to fill the gap in the midst of object-relational mapper explosion.  This is an object-object mapping library.  It is very opinionated and is intended to be used with domain object on one side of the mapping and dtos on the other side.  It is heavy on convention, and dtos will have to conform a bit.  I’ve used it, and the library is solid.  Here’s a clip from the website:

A convention-based object-object mapper.
AutoMapper uses a fluent configuration API to define an object-object mapping strategy. AutoMapper uses a convention-based matching algorithm to match up source to destination values. Currently, AutoMapper is geared towards model projection scenarios to flatten complex object models to DTOs and other simple objects, whose design is better suited for serialization, communication, messaging, or simply an anti-corruption layer between the domain and application layer.

UPDATE:  Jimmy has blogged about the highlights of AutoMapper.