Confirmed, iPhone is NOT using Intel chip:
Source:
http://www.tgdaily.com/2007/01/11/intel_iphone/
PortalPlayer probably in iPhone:
Source:
http://www.google.ca/search?hl=en&q=iPhone+PortalPlayer&meta=
PortalPlayer purchased by nVidia, makes it likely nVidia may have combined PortalPlayer with a handheld 3D chip:
Source:
http://www.google.ca/search?hl=en&q=PortalPlayer+nVidia&meta=