What processor or processors does the iPhone use?

Officially, Apple provides no information regarding the processor and other internal components of the iPhone, simply stating that the handheld is a "closed platform".

However, on January 10, 2007, ArsTechnica proposed that the iPhone may be powered by a Samsung processor, based on a Reuters report that Intel was not providing the iPhone processor and an EETimes article that speculates:

According to a report from FBR Research, the iPhone winners include Samsung Electronics Co. Ltd. (applications/video processor), Marvell Technology Group Ltd. (802.11), Infineon Technologies AG (baseband), Broadcom Corp. (touch screen controller), and CSR plc (Bluetooth) among others.

The EETimes article continues by pondering:

So how many core processors from ARM Holdings plc (Cambridge, England) does that represent? It's probably one ARM in the Samsung video processor. The Marvell 802.11n solution has an on-chip CPU. And then there is the Infineon baseband chip. . . an Infineon baseband, maybe a custom one for Apple, is quite likely to be based on an ARM processor core.

The CSR Bluetooth protocol stack typically runs on a XAP processor core from Cambridge Consultants Ltd. and custom DSP engines when it runs on CSR-provided silicon but it also runs on ARM cores in some applications. . . I make that somewhere between two ARM cores and lots of ARM cores inside each and every iPhone.

Although there was some later speculation that the primary processor might have been provided by Marvell instead of Samsung, when the iPhone shipped on June 29, 2007 the always excellent iFixit disassembled it and learned that the primary processor is in fact an Apple branded Samsung ARM. Marvell provides the chip for 802.11b/g wireless networking, but not the primary processor.

The Engadget blog speculates further that the ARM processor may run at 620 MHz, whereas Gearlog believes that it may run at 667 MHz. Both agree that either speed is quite fast for a handheld device.