Reports from around the internet suggest the first Windows Phone update may cause different problems with phones and may brick them during installation.
Many Samsung owners report an extended delay during the update when the
Zune software fails to complete the update.
Disconnecting the phone from
the computer during the hang up forces a reboot and the original
version of Windows Phone 7 is restored.
Sadly, some phones do
not recover from this failed update and remain in a bricked state.