So can one conclude that the G35x Sport Package contains no true handling upgrades? (as compared with the G35s and Journey) That it is an interior trim package with nice 18" wheels?

Why not drive both and see for yourself?

Because the Sport Package for the G35x was a "late release" for 2008 and they are not at the dealers yet.

P225/50R18 94V Dunlop SP Sport Maxx A1 A/S

Does anyone have pics yet as to what the G35X Sport will look like?

Exactly like the sport now but the badging is in question.

G35XS probably

I heard that it's the regular G35 emblem, with a red "X" like the Sport "S".

...in the Sport model before you say that these are minor changes. The seats are quite different in feel; they adjust to hold you in place better - power adjustable side bolsters and extendable (non power) thigh support. Personally I find them much more comfortable and supportive than the non Sport model seats.

For $1,500 MSRP the extra features seem to be at least worth the money. I think the differences are:

Sport seats (a set of Recaros with these features would be $$$$$$)
18" wheels and tires (all season tires)
Magnesium paddle shifters
Sport steering wheel
Sport front facia

I've read over the brochure and website a number of times but can't seem to determine if anything else is included. It doesn't seem that the suspension or differential are included.

Personally what I'd like to see is a G35X Sport with 6sp manual, but that is unlikely to ever happen.

I don't believe they can change the suspension or differential due to Infiniti's AWD system.