XDA member ieftm and team has managed to develop an HBOOT image which disables NAND protection on the HTC Desire. This unlocks the /system and /recovery partitions, and allows for unsigned ZIP files to be installed, among a few other things. So, it basically allows for more development for the Desire. Please make sure to follow all instructions carefully, for there is a chance of bricking your device.
Originally posted by AlphaRev
HTC implemented security on their newer generation phones. This flag, called @secuflag, controls whether your phone has
it’s NAND or flash unlocked. Most noticeably, S-ON (security on) will read-lock your /system and /recovery partition, to name a few. Also, secuflag controls whether zip files being flashed through recovery or fastboot, are signed by HTC.
The now notorious S-OFF (security off) will disable this NAND security.