Edit: Found that for which I was searching.
Here's the link to the financial reports, for anyone interested.
I think what should be pointed out, that though they state (by law) that they switched the method that they report shipments of hardware from "produced" to "sold" (as in to retailers of course), but they never say that any single piece of hardware that was counted under the old system would not be counted under the new system. In other words, some PS2s (and PS3s and PSPs) might have been counted twice. Though I can't say for sure, I don't know how hard it would be to track which units were already counted, nor do I know what kind of legal laws would arise from this change and how strict those laws are.
If this is the case, then that about explains it right there.
The other thing that probably should be pointed out is that stockpiling goes on during the year, and yes, everyone does it. This is another reason why the whole "counting some hardware twice" might happen, because they would have units sitting in warehouses and calling them produced, and then after the new fiscal year started, they would sell them and count them again as sold.
But when it comes right down to it, someplace must not get tracked (mainland Asia maybe?) because Sony said (one way or the other) that they produced 117 million PS2s by March 31, 2007, yet here we are nearly a year later with only 116 million sold. It wouldn't surprise me if there were more PS2s sitting on the shelves compared to PS3 and 360s, simply because it sells so well all year (and has for the last 6/7 years), is cheaper (thus easier to get rid of), has a great library (more people willing to pick it up on a whim), and some other reasons. Sony might have overestimated demand as well, and retailers have been willing to buy PS2s, and Sony has stocked some as well.
There's a lot of different things that could cause this great (nearly 12 million) difference, but it could be a combination of what I have mentioned, or something completely random (they had 12 million PS2s in a warehouse that burned down?).
