On the Official Web site the PSP v1.51 firmware update is now available for download for JAP region PSP users. Those interested in simply examining it can grab the v1.51 Firmware Update, however, unless you actually own a JAP PSP and wish to have the latest firmware equipped we recommend NOT updating with it at this time. Several dev'ers have already confirmed WPA protection still hasn't been implemented in the update and also unencrypted (homebrew) code does not run with it. For those interested in the file information:
05/11/2005 02:10 AM 10,937,520 DATA.PSAR
05/11/2005 02:10 AM 3,704,304 DATA.PSP
05/11/2005 02:10 AM 11,261 ICON0.PNG
05/11/2005 02:10 AM 1,580 PARAM.SFO
4 File(s) 14,654,665 bytes