Playstations official Japanese site announced the UMD case present promotion for their slated titles.

If a customer pre-orders any of the titles in this [List] from Playstation.com, he/she will recieve a promotional UMD case at no charge. Each case can hold one PSP UMD disk, and the cases can be attached together for the convenience of storage.

The expiriation date of this promotion is per title, as the promotion expires on each of the UMDs' respective launch dates.

site officiel