I was in an Apple Store (Delaware) the other day...with $500 in my pocket and a strong desire to buy in a state where there is no sales tax. I've been running a 400mhz G3 with 10.2.8 and 192mb of RAM.
I expected all of the new machines, even the mini, to be blazingly fast compared to my 6 yr. old computer. They simply weren't. I know that there is probably a huge difference in the overall experience, they just didn't feel faster.
I was still ready to buy a mini until I checked the specs on the display models. Every display machine in the store had at least 512mb of ram.
If the display is an upgraded model, and even that doesn't quite feel right, the 256 mb standard is definitely not enough. If they won't even put a true standard model on display (I believe out of embarrasment), why do they offer it. The people who come in to switch are not going to like it when they find out that what they have at home doesn't even come close to what they used in the store, because they didn't spring for an upgrade (which the store wouldn't even have done on the mini at that time because they didn't have the kits in yet).
For the people who skim and then read the bottom line, there is at least one apple store in this country that won't even display a machine that has less than 512 mb of RAM, they shouldn't feel right about shipping them.