Note that there was some confusion regarding the various methods of "detecting RAM size via software (i.e., from within the OS)". Specifically, a) you had to be running the latest firmware and b) there was some chatter to the effect that the "Revision" thing (in /proc/cpuinfo) wasn't reliable because it wasn't set right in some production runs (and/or that it was being fudged in software).
For these reasons, I share the OP's concern that it would be nice if you could tell (definitively!), from the outside, what the hardware is. I, too, tried to read the markings on the chip, but could not do so, even with a magnifying glass. Note: My machine is a 512M, of this I am quite confident, so I'm not looking for help on that score, but, as I say, it would be "nice" if the "reading the chip" method was reliable. Maybe I need a higher power magnifying glass...
And some folks need to stop being fanboys and see the forest behind the trees.
(One of the best lines I've seen on this board lately)