Coincidentally, we appear to have fried a card after moving it in and out of our own Focus today to the point that no PC, phone, or camera can read it anymore, so this is definitely a real problem that needs a real solution. It's odd that Microsoft appears to have been fully aware of this situation prior to release and yet AT&T's only now drawing the line, but we can't even imagine the kinds of bureaucratic head-butting that happens between corporations the size of AT&T, Microsoft, and Samsung. In the meantime, be careful out there, folks."Windows Phone 7 requires a certified high-speed microSD card for optimal performance. Because the Samsung Focus is expandable via a microSD card, only microSD memory cards certified for Windows Phone 7 should be used. This information is not currently marked on any microSD packaging in market today. As a result, we are advising customers to delay purchasing an external microSD card until the cards identified as "Certified for Windows Phone 7" are available commercially or in AT&T stores."
But what appears to have fried our card is the fact that any card inserted into a Windows Phone 7 device "will no longer be readable or writable on any other devices such as computers, cameras, printers, and so on" according to documentation on Samsung's site -- including, amazingly, the ability to format the card. That's hardcore, and it also explains why these guys are so skittish about external storage in general and why so few WP7 devices support it at this point."Determining whether an SD card is Windows Phone 7 compliant is not a simple matter of judging its speed class. Several other factors, such as the number of random read/write operations per second, play a role in determining how well an SD card performs with Windows Phone 7 devices."