I think the difference between Wii vs. 360 and 360 vs. PS3 can be seen in a few things:
1) Wii shipped a year after 360 and yet has sold 14 million more - that's pretty telling.
2) PS3 is 6+ million behind 360 but shipped a year later, so it's hard to say just yet how that will play out.
3) Wii is still outselling 360 by a large margin even now that 360 is available at a lower price point - PS3 is still far more expensive than 360 - we don't know for certain what will happen if/when that changes.
4) Because PS2 was so successful, there may still be plenty of PS2 users who are waiting to get PS3s.
That said, I personally think that the 360 will remain ahead of the PS3 for the rest of this generation, but it's definitely not as simple as comparing the gap - there are other factors that play into the long term success of these platforms.
