The Leica Q has been officially announced by Leica: Leica-camera.com. I will keep updating this page with links to preorders and reviews:
Previews, reviews and hands-on:
Review by Ming Thein. Review at ThePhoBlographer. French test at Lesnumeriques. German review at SystemKameraForum. Review at LaVidaLeica. Hands-on at ePhotozine. First impressions review at Dpreview. Hands-on at Dpreview. Image samples at Photographyblog.
Video interview at Luminous Landscape.