Tactial mentions on the forums that all of the Rogues (in fact, this is true about almost everyone) are still in Tier 4. When Burning Crusade first came out and we all reached 70, Tier 4 was where it was at -- some people were excited about being in Tier 4, even if they hadn't earned it yet. But nowadays, Tier 4 ain't that great, and yet all of our forum icons shows us in the (now old) armor.
Drysc does say that the Armory is a click away from the forum icons, but surely Blizzard could take an afternoon and code a little customization into the icons. It seems like everyone else can render icons out of game -- why can't they? There is some good news for those looking for a forum icon update, though: Drysc says that when we're all level 80, we'll probably have new icons yet again, with shiny T7 on our characters.
Which will be great -- until a few big content patches after Wrath, when T9 will be out and we'll all be whining that we're still dressed in T7. Thus goes the circle, the circle of life.