While Sony’s been busy leveraging its existing franchises such as God of War, Buzz! and now Resistance for the PSP, Sony Worldwide Studio boss Shuhei Yoshida’s admitted he’s not happy at the lack of third party titles on the horizon for the portable.

“What we'd like to see more is for third parties also – there is so much great IP that they have,” he told IGN.

“… It's really, really disappointing and it's a lost opportunity for the third parties,” continued the man who filled Phil Harrison's shoes at Sony. “They should look at what the PSP can do for their titles and the potential for the business that their IP has.”

Yoshida went on to say that Sony needed to show third parties examples of how externally developed PSP games were successful, citing the system’s strong performance in Japan, where the handheld currently leads 2008 system sales and also boasts the year’s bestselling game, Capcom's Monster Hunter 2nd G.

“We have to show by examples. What's happening in Japan is interesting - because of the massive success of Monster Hunter, Japanese publishers realize, 'here's a resource'. Lots of people are playing PSP in groups of fours and when you go to Japan it's hard to find a train or a bar where you don't see some people playing a PSP. So other publishers in Japan are seeing these consumers, and thinking, 'Wow, we can make games for those consumers'.

Check out the full interview for talk of fresh Sony IP, including the new Team Ico game, and the importance of the PlayStation Network to the PS3’s ten-year lifecycle.