Sorting out a MicroSD card for your WP7 device is tricky. Very tricky. We’ve heard all sorts of different claims about what cards are and aren’t okay, but the eventual truth is that they need to be certified usable by Microsoft and the OEMs. Well, we may just have heard word of the very first officially approved card. On Samsung’s support page for the Focus it says the following:
Compatible micro SD cards will be branded as “Windows Phone 7 Compatible” on the packaging. Approved cards can be obtained from the manufacturer or carrier. (The SanDisk 8GB class 2 micro SD card has been certified.)
It’s all very confusing right now.
Samsung does go on to warn that inserting a MicroSD may make it non-functional on other devices:
Once inserted and properly formatted, the memory card becomes an inseparable part of the phone. A micro SD card inserted into a Windows Phone 7 device, and integrated into the device’s file system, is intended to be a permanent modification to the device. Once a micro SD card has been integrated into a Windows Phone 7 device’s file system, it will no longer be readable or writable on any other devices such as computers, cameras, printers, and so on. This includes an inability to format the micro SD card for use in these devices.