Here are some details from Previews, on page 329 in the Last Gasp section of the catalog.
JUN08 4100 TOKYO ZOMBIE SC (MR) (C: 0-1-2) SRP: $9.95
The release date is pegged at September 2008, and Last Gasp will have some advance copies at San Diego Comic-Con to show off at their booth. Here are details on getting a copy:
Tokyo Zombie will be available through your local bookstore of comic shop, and you can ask that they order some copies via their distributor to ensure you get yours! Naturally, it will also be available online via Last Gasp, Powell's, Amazon, and other book retailers.
For bookstores or comic shop owners:
Tokyo Zombie can be pre-ordered from Last Gasp, or through Diamond and other book distributors and wholesalers.
For folks overseas:
Tokyo Zombie will be available at many stores worldwide or can be ordered through Last Gasp. Overseas store owners should contact Last Gasp for more information.