Hello,
Sometimes, I think we forget that the
SD in SDHC means
Secure Digital because so few devices make use of the function to encrypt the card. Windows Phone is, of course, one of those devices, as mentioned in
this blog post on MSDN.
Many Nokia phones (E71, N95, N97 mini...) recognize encrypted cards and will offer unlock them via reformatting. This may also be doable in some Windows Mobile 6.5 devices.
Alternatively, see
this longish thread on XDA Developers for information on how to unlock a card via a Windows Phone 7 device.
Regards,
Aryeh Goretsky