Having several memory cards types available is simply too much. In our opinion on the long run only four standards will be alive: CF, MS PRO, SD and xD. MultiMediaCard (MMC) and SmartMedia (SM) are pretty dead right now, specially because of their very low transfer rate. In fact, xD was created to replace SmartMedia (SM) and SecureDigital (SD) was created to replace MultiMediaCard (MMC). MS has a low transfer rate compared to newer standards, but Sony pushes this standard really hard, so we will be seeing Memory Stick alive for some years, until it is completely replaced by MemoryStick PRO, which provides a really good transfer speed.