Is this walnut?  

Possibly.
Need an in-focus closeup shot taken in good light with no glare to better guess. Higher resolution image would help, too.

Does anyone have a useful...
Does anyone have a useful source that can help me identify different wood species? Sometimes I think I'm color blind......

Hmm
Is there a manufacturing sticker on the underside with the veneer code? The grain on the seat does not look like the typical walnut for Eames plywood chairs.

It looks like cherry to me
but I'm certainly no expert.
Here's a wonderful site for identifying wood species:
http://hobbithouseinc.com/personal/woodpics/

I'd say that it's cherry.
.
Aunt Mark

Woody, there's a faded and un...
Woody, there's a faded and unintelligible label on the bottom which doesn't tell much.
I agree that it doesn't look like a typical walnut but it seems a little to grainy to be cherry to me. Btw, the website that Spanky provided is pretty ridiculous; ridiculously informative is what I mean =) Thank you, Spanky.

It's
an awful nice chair.

Cherry, I'd say;
a closer pic would help. Plain-sawn cherry grain like this often shows a second stripe next to the darkest one, of a slightly different color.

Additional pictures. My...
Additional pictures. My untrained eye still says walnut......

Yes
Back rest and underside of seat definitely look like typical walnut veneer. Not sure why the top side of the seat looks so different.

UV exposure
It happens to the best of us.
http://forums.finewoodworking.com/fine-woodworking-knots/wood-and-materi...

That looks like walnut to me....
That looks like walnut to me.
UV exposure could have made it look so cherry. It also could be the color balance of the photo.

Grain
I was referring more to the grain. I would think that the top and bottom side of the seat would use the same sheet of veneer. I could be wrong though.

.
A hybrid, perhaps?