Image source: clampProject.
XXXHOLiC Rei #1 will be released on October 23rd. You can watch the trailer of the first part of "XXXHOLiC Shunmuki" here.
More details as they come! I hope CLAMP gets to draw a new cover art =)
Update: Kodansha's XXXHOLiC portal site has more information about the release.
Apart from the remastered version of "XXXHOLiC Shunmuki", the Blu-ray will also come with the the first episode of the XXXHOLiC TV Drama. A special postcard will be included as well. This limited edition will go on sale for 5,250 yens.