Yeah those threads are cool and very very long. I love browsing conceptart, although im too scared to post any of my stuff there.
I've yet to see anything from GW:EN, the factions and nightfall stuff wasn't posted until both games had been out for a while though so there's a strong chance it will pop up eventually.
I think there's a Prophecies thread somewhere but I can't find it. Maybe it's been archived or something, since at the start of the Factions thread the poster said "its been a while since our last post..."
As for GWEN, I'm guessing it'll take a few months for them to get permission to post their newer stuff.
This isn't really anything I haven't seen before but I'm a big fan of the GW art team, have been ever since I started playing. Esp. Tinfoil's/Daniel Dociu's collaboration paintings continue to amaze me. I only wish I could find a Prophecies CE version of the game somewhere for a student-affordable price hehe. :P
I don't remember there being a prophecies thread though but then again I only started playing sometime after Factions' release(not even a year ago).