Heh, 244mm^2. I have a feeling you're way off because:
a) We don't know that PSV is being manufactured on 45nm and not 40nm, and we don't know who is manufacturing it
B) L2 cache takes much more space than Cortex-A9 cores which, even with NEON, will take under 5mm^2 each. And PSV probably has 1MB of L2 like the other high end A9 SoCs.
c) They probably have roughly the same uncore, memory controller et al
d) And video engine which takes a lot of space (look at a floorplan of the original A4 for instance)
e) I'm told by private sources that A5 includes copious amounts of dedicated RAM for the SGX543MP2 (this could be texture cache, tile memory, parameter queues, whatever)
Don't be too surprised if the PSV SoC is closer to 1x the size of A5 than 2x. Of course we might not know if no one bothers to dissect it.
In the real world density is not a simple function of what metric the process is advertised as. If you compare say, Apple's original A4 on Samsung 45nm with Tegra 2 on TSMC 40G or whatever you'll see that the densities don't add up using a simple numerical comparison. Similar story for Zacate cores which, going by transistor counts, look something like twice as dense on TSMC 40G as Atoms on Intel's 45nm SoC process. Of course, what you're actually manufacturing plays a large role as to how dense it is, but there are tons of parameters in the process which affect this too.
Mind you, die size is not the only factor for price. Yields have an obvious impact too, which both process and design impact.
OMAP5 is going to be SGX544MPx, where I hear that the x will be available as both 2 and 4 (possibly not both initially) - and it's expected to clock pretty damn high, probably much higher than Vita can be clocked to. I also think the 2 Cortex-A15 cores will have little problem giving Vita's 4 A9 cores a run for their money, especially since I'm hearing that the A9s in Vita won't even hit 1GHz, while OMAP5 will be available in excess of 2GHz. And on Vita the OS is hoarding one of the cores, as usual.
This is completely ignoring ST Ericsson's upcoming Nova Thor with Series 6 Rogue GPU. Hardware-wise I don't think it's going to take long at all for other devices to beat Vita, certainly not needing 20nm (not that I really think anything ~20nm will be available in 2013, not counting 22nm products from Intel)
Everyone is going on about how huge A5 is but the only real datapoint for comparison that has been used is nVidia. nVidia who is so cheap with die space that they didn't even give their Tegra 2 cores NEON. There's no information on how large TI, Samsung, or Qualcomm cores are (for starters). We do have some information on Atom SoCs and they sure aren't small, although I guess that's not too relevant given what margins Intel sells those for.
