The source is likely screwed up, considering the PS2 is still outselling -everything else- in all regions except maybe the US.
I don't know where you pulled your figures out from, but the PS2 is being (and has been) outsold by the DS, the Wii, even the PSP in Japan alone. Then you've got the Wii or DS being top seller in Australia, Canada, USA, etc. Even with limited supply of both DS Lite and Wii hardware, they're still winning by a huge margin. The only thing the PS2 consistently outsells is the PS3.
Nothing's changed. Nintendo have another Game Cube on their hands and Sonys PS3 will be selling a good 5 years from now, if not closer to 10.
Yes, nothing's changed except for exceptionally high sales, and being sold out everywhere. Whereas the PS3 can't even outsell the PS2, and it's not a supply problem.
The raw processing power of ~100,000 PS3s is roughly equal to that of ~20,000,000 PCs, if you use Home as a benchmark.
The Cell CPU is almost perfectly designed for getting high numbers in Folding@Home. Almost perfect because the newer ATI and nVidia programmable GPUs are way better than it, cost the same or less (and continue to get cheaper) and plug right in to most PCs.
You've got Quad Core CPUs soon becoming standard on PCs which are also better than Cell at Folding@Home, and impressively loads of other stuff too.
Of course by then, prices of newer ATI and nVidia GPUs will come down, and quad core CPUs will be commonplace, thus continuing to kick ass.
Also, I don't know where you heard that Microsoft would be using Cell in their next system.
That said, I'm sure sales of the PS3 will pick up whenever all the rabid Final Fantasy fans can get their fix on it. I'm sure the 360 will also get some sales when Halo 3 comes out. In the meantime, in spite of the Wii apparently having no clear "console seller" it's doing better than everyone else.