The PSP that is on sale in Japan will be different from the
PSP's that will eventually launch worldwide. The difference is the
screen. The Japanese PSP's will have a screen made by Sharp whereas
the Worldwide version that will be released outside of Japan will
have a screen made by Samsung. The Sharp screens are apparently
better quality. I haven't seen the quality of the Samsung screen so
I cannot comment on that.
Also all games can be played in Japanese or English as it allows
you to choose. All the games are region free but the region coding
still applies for films. There are already devices on ebay which
allows you to play all regions. Strange, as only Japan have
released films for the PSP so far.