Portland Transport has the skinny with photos and a video. With the recent passage of the Eastside Extension, it looks as if there will be a lot more of these coming. I've also heard rumors that Tuscon could order from OIW as well.
As a side note but not entirely unrelated, the Wall Street Journal ran a piece on how places like Portland and Austin are hitting a mid-life crisis. They are getting such a huge influx of past college folks that there just aren't enough jobs for them. But why are people moving there? What makes these places cool?