Here's a list of Forthcoming Titles (please note that all dates are subject to change) :
Rare Birds of North America
Owls of the World (2nd edition)
Sibley Guide to Birds (2nd edition).
The Helm Guide to Bird Identification (European species).
Phillipps' Field Guide to the Birds of Borneo.
Pigeons and Doves of Australia
Woodpeckers of the World: A Photographic Guide
Ducks, Geese and Swans of North America (3rd edition)
Birds of Ecuador
Birds of New Guinea (2nd edition)
Birds of Brazil
Birds of Taiwan
The Eagle Owl
Peterson Field Guide to Bird Sounds
Birds of Mongolia
TO BE ANNOUNCED:
Raptors of Mexico and Central America
A Field Guide to the Birds of China
Birds of Paradise and Bowerbirds
Collins Field Guide to the Mammals of Africa
Peterson Reference Guide to Woodpeckers of North America
Peterson Reference Guide: Birding by Impression
Birds of the Southwest Atlantic & Antarctica
The Crossley ID Guide: West, Warblers (with Alvaro Jaramillo), Ducks (with Jessie Barry) and mystery guide.
Birds of Argentina
Hummingbirds of the World: A Photographic Guide
Birds New to Science
The Barnacle Goose
Dawn Chorus in Eden
Birds of the Guianas
Handbook of Western Palearctic Birds: Passerines