The fact that it seems to be happening with all consoles indicates that it's probably not something specific to any one of them. I think it's a lot more likely to be some kind of snafu in shipping, or possibly even a disruption in the stores' buying patterns, than an indication of any premature "new model" coming out from any of the big three.
And they would be premature. The Wii is still dominating over the industry with an iron fist, the PS3 Slim hasn't even been out for a year yet, and Natal isn't ready but is close enough that it makes more sense for Microsoft to wait for it than to do two back-to-back refreshes. It makes no sense for any of the three console makers to release a new model right now. None whatsoever.
Complexity is not depth. Machismo is not maturity. Obsession is not dedication. Tedium is not challenge. Support gaming: support the Wii.
Be the ultimate ninja! Play Billy Vs. SNAKEMAN today! Poisson Village welcomes new players.
There is much to hate about modern gaming. That is why I support the Wii.