Sony doesn't seem to think Game Boy Advance is a thread to PSP, with SCEE president Chris Deering recently describing the company's planned portable as "synergistic and dynamically collaborative with Game Boy", and it seems Microsoft has a place in its heart for Nintendo's diminutive handheld and its overpriced software, too.
MS has long planned to produce titles for the console, signing THQ up to publish versions of big PC titles like Monster Truck Madness, and it looks like Rare's previously planned GBA titles could still appear on the system under Microsoft's control. Diddy Kong Pilot was one title Rare was working on before Microsoft stepped in, and C&VG reports that according to the official US Patent and Trademark site, Microsoft registered the name "Banjo Pilot" on July 3rd this year, suggesting that Nintendo's intellectual property has gone out of the window in favour of its own.
Microsoft is of course refusing to comment on this, but September's X03 might be the time to announce it, and Rare's website currently makes reference to a new publishing deal. So who would publish Banjo Pilot? THQ, presumably.