There is a video on Youtube of young hacker Jeremy Way showing how he hacked his DS to play his PSP UMDs. Some commenters have called shenanigans but it looks quite convincing. He started the project by taking apart a new PSP device and using the chipset on a home made board creating an adapter with r4i sdhc parts. This does look very tedious and time consuming and the finished project is not a pretty site. But what can you say. This is an innovation to try if you are really that savvy to dive into this project, just dont mess up!