[PapstDFrisco]

As a hardware engineer who designs ARM based embedded systems for a living. Overclocking one of these systems will not be a trivial task. Unless, they purposely left headroom in the design - then it would be fairly easy. In a PC you get to select the speed of your memory. In a system like this you have what you have because it's mounted on the pcb. Most PC motherboard have programmable clock generators too, most systems like this don't. Most ARM systems use a standard frequency clock and use on chip pll's and system registers to select the output frequencies.
So, your only hope, is that the processor is not running at it's max already. Because getting a higher clocking rate is not trivial in an embedded system like this.

I'm not saying it can't be done - it's going to be either really easy or almost impossible - and the later is much more likely.

It's also the same thing for a memory upgrade on the Mogul/6800, the chip is a 2G/1G flash/ddr hybrid in a BGA by the looks of it from Samsung. Internal Pics of unit on XDA forum. I don't know how many of you have replaced a bga - but again it's non-trivial.
Again, could be done, just not easily - unless you have access to the proper equipment.