Obviously, everybody expects a drop off after the first week a new console goes on sale, but such a dramatic drop is really shocking. Nonetheless, Chart Track itself says that the number is "meaningless" because of all of the pre-orders, high demand because of the delayed launch, and the fact that so many PS3s were stockpiled that there were actually PS3s available in the second week, as opposed to the launches of the Wii and Xbox 360 which had no stock the second week.
On a brighter side, the 165,000 PS3s sold in the first week is the largest console launch in UK history.
Personally, I think that the numbers are meaningful. The demand wasn't so great that they actually sold out of their nearly 200,000 consoles, so the fact that they had consoles for the second week is significant and shows weakness and an early saturation. The Wii is outselling the PS3 everywhere and that will continue to be the trend until there is either a price drop or some compelling reason (a game? a service?) to make people want to pay that much. I know I don't.