Or from Sony themselves
CAUTION: This update is only for customers who obtained PSP® (PlayStation®Portable) for Japan which model number is PSP-1000 or PSP-1000 K. Upon completion of preparing, we will announce update information for the other countries/areas customers via SCE Group Web Site or other channels . For these customers who obtained PSP® in the other countries/areas, please DO NOT update PSP® through this web site. There are no guarantee of proper operation of the other PSP®.
My question though is why? The upgrade does work, and it works great. It's both in Japanese and English, so that's not the issue. What changes could Sony have planned for the English version of 2.00?