In a statement Friday, AT&T warned users that the Windows Phone 7 devices are not compatible with ordinary market microSDHC cards. They must instead by specialized Microsoft certified microSDHC cards, otherwise they will cause the devices to run unacceptably slow and build up data corruption. An article from the Inquisitr gives us the scoop,

According to AT&T users will be able to do a one-time storage upgrade once the new “Certified for Windows Phone 7″ cards arrive in stores.

The wireless company said the cards are faster than standard microSDHC cards and that the “optimal performance” is necessary for use on the new higher-end devices.

Optimal performance seems to be a bit of stretch when the cards run okay for a while and then fall into a pit of despair, grinding-slowness, and data corruption; but we’ll let AT&T have their day. People using Windows Phone 7 devices who don’t have a “certified” microSDHC card yet really should look into when their stores will receive them, get in, and get upgraded—otherwise a terrible malady could befall their smartphone.

Despite the dismal shortcoming, Mark “Rizzn” Hopkins puts things in perspective reminding us that “this is actually quite common for many devices, including photography and video cameras, where the write level must be of a certain speed. Many of the cameras and devices we use for our work with #theCube have this same limitation.”