Best example that I can think of off hand is EA Mobile. They've invested quite a but now into the iPhone / iPod touch.
Yep, they've invested more than some of the others but the EA games being released for iPhone aren't a patch on the PSP efforts. They either lack the depth that a PSP game has (The Sims 3, SimCity) or the controls fail the gameplay (NFS Undercover).
While it would be nice to see some decent, in depth games coming to iPhone, it's never going to happen while Apple allows developers to price their applications at 59p - there's just no room in the market for better things.