A number of Japanese games do have english (and other languages) in them, which you can select by setting the language in the system options. Soul Caliber IV and Winning Eleven are two games that support this (the same applies in reverse too) (and my aren't the cheesy american voices in SCIV really grating), however not all games do. Is there a list anywhere of what languages games support per region?
I would like to find out if the Japanese version of Little Big Planet has Stephen Fry's lovely wit. It would be nice to see what other Japanese games do support English too. The Chinese/Taiwanese/Hong Kong PS3 games do state on the back of the box what languages they support, and LBP does have English as well as Chinese (although not tried other languages...).