The Wii price drop won't have near the effect that people hope. It was already the cheapest and the market is well saturated. I think people are putting far too much faith in system selling games for the Wii - I'm not saying they aren't big titles, I'm just saying the majority of people who want them already have them. With the PS3, it's the exact opposite.
I think PS3 will do it, but we'll wait and see. The numbers range quite a bit between the two, but I expect neither console will be more than a week or 2 off of that 'landmark' either way by time the first console reaches it.