I think you have to wait until Sony actually bothers to updates their web browser for better flash support.
http://community.eu.playstation.com/.../td-p/15682047
The link talks mostly about Flash 10 problems but I'd assume Flash 9 and below might still have some problems with the web browser.
Don't own a PS3 myself but heard for years how horrible flash support is for the web browser. Some of it was related to when it used to have and then lost Linux and others due to the closed nature of the browser (custom made?).