Poison ivy v. Poison oak
Yes, this looks like poison oak. Hikers (and their dogs, small children, etc.) should watch out for coming in contact with itch-inducing oils on the leaves.
Here is more information for how to identify and avoid poison oak, how to remove its oils from you, your pets and you gear, and how to remove the plant itself from your site.
Poison oak is a native plant in Oregon and its berries are a food source for birds, so it's not all bad - just not great to have where people spend lots of time.