We finally have an idea of when the PSP accessible PS Store will launch: this fiscal year. Previously detailed in a GDC presentation last year, the PSP Store will allow consumers to download PSN offerings direct from their PSP via WiFi connection.
At its marketing conference in Japan today, Sony said that the functionality will be made available through a firmware update. The company's 2008 fiscal year ends on March 31, 2009, so the launch date could be anywhere from now until then, though we're personally hoping it hits before the end of this year.