How Uncharted 2 set the technical benchmark (extensive read)

[Reasonable]

I'd still give the nod to Uncharted 2 over Gow3 on PS3, technically.  The engine is simply more robust overall (at least on the evidence of the games themselves) in terms of the gameplay variety it can support, plus it paved the way for much of GoW3, particularly in how it pioneered an engine with large, truly moving entities (the train being the highlight of course).

It also contains by far, I'd argue, the two most impressive levels, the train of course where you are actually traveling through what feels like endless, real surroundings, and the Tibeten village, where the detail of the houses, characters etc. makes GoW3's levels seem pretty barren (and in fact in terms of detail level they are, in admittedly trademark style for the GoW series) of details next to Uncharted 2.

The animation in Uncharted 2 is also more consistent.  The monsters in GoW3 are amazingly animated, but Kratos still doesn't have a proper walk animation and many of the Gods featured looked very poor for character animation - in Uncharted 2 all characters are amazingly well animated and there are none of the blips that sometimes caused me to lose immersion a bit with GoW3.

GoW3 is perfectly polished for the type of game it is, and due to less detail overall it can push superior lighting and frame rate as well as plenty of it's own fancy effects and touches, but while the engine may be capable of more from the content in the game it feels limited to a few, specific gameplay elements, whereas Uncharted 2 covers pretty much every gameplay type apart from vehicle driving (which I missed but they clearly removed due to grumbling about their poor control choice of the jetski in Uncharted).

In comparing them, though, I feel the overall difference is minimal and it's a very close thing: a ball hair's difference as it where, if you'll pardon my French.

BTW for those wanting to read up more on Uncharted 2 I'd suggest Digital Foundry's good coverage of the title where they delve into all the cool innovation packed into the title.

EDIT: As Boutros also notes, the ability to support such great online play is another testiment to how flexible Uncharted 2's engine is.  I can't wait to see the next version which is sure to feature even further optimization from Uncharted 2.