A paper describing Wannier90 is now available:
Wannier90: A Tool for Obtaining Maximally-Localised Wannier Functions
A. A. Mostofi, J. R. Yates, Y.-S. Lee, I. Souza, D. Vanderbilt and N. Marzari
Comput. Phys. Commun. 178, 685 (2008) [ONLINE JOURNAL]
Wannier90 paper
April 16, 2008