Ehhh...no, not really. The sun is pretty much ALWAYS on you with the way The Gorge is set up. Once it starts going down though, the pit right in front of the stage is the first to catch some shadow due to the setup blocking it.
Bring lots of sunscreen, a hat, and an extra shirt or towl to cover your neck and you'll be just fine. Do NOT get burned though, otherwise you're in for one uncomfortable weekend. '08 pretty much guaranteed that I will someday be rocking the melanoma.