The Moods of Homeric Greek was published in 2007 by Cambridge University Press, as part of the Cambridge Classical Studies series. It is available at all good bookshops, including Amazon. Full description as well as a table of contents and downloadable index is available from CUP.
It has since been reviewed in several publications. References and links where available follow:
"...a stimulating and thought-provoking book... W. demonstrates that a clearer picture of complex grammatical categories may indeed be gained by consistently considering the data from the viewpoint of grammaticalization."
"...ihre Überlegungen [sind] sowohl für den Sprachwissenschaftler als auch für den Homerphilologen stets anregend, so daß beide das Buch mit Gewinn zur Hand nehmen werden."
"The synchronic analyses of the Greek moods in the book are excellent: they are more sophisticated and detailed than those found anywhere in the standard handbooks. Close study of this book will make one a more semantically sensitive and thus better reader of Greek."
"...essential reading for those interested in the Greek moods... Overall, while readers may disagree with W. on some points, they will no doubt be stimulated into reconsidering exactly what the Homeric moods do: Attic this certainly is not."