He's talking about current sales rates, not total lifetime sales.
Weekly DS and PSP sales are running around 350k per week these days.
Sales of iOS devices are running around 230k per day, or 1.6 million per week.
If iPod Touch = 22% or more of iOS sales, then statement = true.
It's really not as outlandish a statement as it sounds. DS and PSP are well past their peak, and the iPod Touch is still gaining steam as the hardware and software environment get stronger every year. One of the nice things about iterating your product every year is that saturation becomes a much smaller problem.
Edit: Sigh, fixed my use of the unsupported plus sign. No wonder these forums can be so negative. 
"The worst part about these reviews is they are [subjective]--and their scores often depend on how drunk you got the media at a Street Fighter event." — Mona Hamilton, Capcom Senior VP of Marketing
*Image indefinitely borrowed from BrainBoxLtd without his consent.
