Let me describe what I see on my MacBook Pro, and maybe we're talking about the same thing...
When I look closely at the screen straight on, it appears kind of grainy like you say... But I refer to it as sparkly or shimmery, and as you tilt the screen forward and back, the color uniformity is very uneven. It starts getting much darker at the top as your viewing angle gets lower. The effect is so strong, it makes looking at a solid color background like looking at a gradient.
When doing the same thing on my Powerbook, the brightness changes as you tilt the monitor, but the color fades uniformly (meaning it doesn't just get dark at the top first, it changes all at once).
For what it's worth, I've seen some 15" Thinkpad screens that are exactly the same way. That's part of the reason that I bought a 14.1" Thinkpad for myself. I certainly hope this isn't a trend on new laptop displays...