The amount of spin is directly proportional to the length of the press release. I like how Ninty's is short, and to the point.

The more words, the greater the spin when it comes to something like that.

Its also sort of embarrassing how the "Playstation Family" got close to being outsold by the DS - ignoring the Wii completely.

I think if NPD were grossly in error, we would see that reflected in the corporate spin. I don't think they would say it like that, but we would hear something like:

The launch of GTAIV kicks off an incredible month of PS3/X360 sales for May.

However, there is no such statement which leads me to believe their internal data is consistent with NPD.  Sony hints at better sales, but it's kind of buried.

There is not even the slightest remark that contradicts the NPD results in any way. Contractually they are obligated not to criticize, but there are many ways to say sales were better than reported without breaching any contracts. 

So MS talks about how it had a year start and Sony talks about how it sucked even worse last year, both trying to hide the fact that they're sucking now.

Again, do you actually expect them to admit that?

Of course there are better ways to put out releases, but just saying "We're pleased with out sales, and hope you enjoy our games," would get accused of denial as well, even though that's probably they best thing to do here.  

Wow, not only did they calculate attach rates, they actually computed the ratio between attach rates as a percentage!

Just when I thought I had seen all possible spin doctors' tricks...

MS: Xbox 360 games accounted for three of the top ten games in April

Um... I only see two (GTA4 and CoD4).