You can make part of your move up and along walls.
Benefit: As long as you are no more than lightly encumbered and suffering an armor check penalty of no more than –1, you can take part of one move action each round to traverse a wall or other relatively smooth vertical surface if you begin and end your move on a horizontal surface. The height you can achieve on the wall is limited only by this movement restriction. If you do not end your move on a horizontal surface, you fall prone, taking falling damage as appropriate for your distance above the ground. Treat the wall as a normal floor for the purpose of measuring your movement. Passing from floor to wall or wall to floor costs no movement; you can change surfaces freely. Opponents on the ground can make attacks of opportunity normally if you leave a threatened space (even if you leave it by running up a wall).
Special: You can take other move actions in conjunction with moving along a wall. For instance, the Spring Attack feat combined with Wall Runner allows you to make an attack from the wall against a foe standing on the ground who is within the area you threaten as you run past on a wall. However, if you are somehow prevented from completing your move, you fall. Likewise, you could make Acrobatics checks while moving along the wall to avoid attacks of opportunity from leaving threatened spaces.