Yes, Charlie; the right half of the prop pulls harder than the left half while the tail is down and dragging and the plane is rolling for take-off.
Then, while the tail if lifting and trying to get in line with the nose, the pulling of both prop halves tend to equalize.
However, at the same time, there is another force named precession, which pushes the engine shaft directly across from right to left, and makes the plane pivot or yaw over the wheels.

If you are taking off in a crosswind from left to right, then another lateral force over the vertical fin adds to the equation of left yaw.
When the plane starts lifting the nose and taking-off, the direction of the precession force reverses and pushes the prop nose from left to right.

Since the tail and the nose of a trike stay at the same level during take-off roll, the left yaw caused by those two forces (P-factor and precession) is minimum or null.
That is why the easier trainers for take-off's are trikes.

Check this video:

http://www.youtube.com/watch?v=vWsuX...eature=related

The precession force resists the wheel from returning (falling) to the horizontal position, while induces a rotation.