Oh, I am loving this discussion and am sorry I came so late to the party.
Max e^{i pi} says
Will such a collision do damage to the ship? Most likely yes. A lot less energy will be released, but it will all be focused on a relatively small (pea-sized) section of the outer hull. Depending on the material and construction techniques involved, it may very well pierce the hull.
When dealing with hypervelocities (this is defined as anything faster than about 2 km/s, or roughly 4500 miles per hour), collisions behave very differently than what we are used to in every day life experiences. Below is a picture of one such impact, where a 12mm (~0.5 inch) aluminum ball hit an 18 cm (~7 inch) aluminum plate at 7 km/s.
As you can see, the resulting crater is much bigger than the ball that created it. (Note, this is not the original ball that formed this crater. That ball would have been vapourized by the impact. This is a different, same-sized ball, shown here for comparison.) Also, the effects of the collision are not confined to the crater. Notice how the back of the plate has separated from the rest of the plate, even though the area between the crater and delaminated part *looks* untouched. This is showing that there's a lot more damage happening than what can be seen.
So, hypervelocity impacts are great fun and very destructive! I wouldn't want to be on a space ship that was hit by one, even if the projectile was only pea-sized.
However, as Max e^{i pi} alludes, construction techniques can make a big difference. Making the ship's skin from multiple layers does help (see below).
Anyway, I hope some have found this interesting. I study impacts for a living (but on planets, not spacecraft), so this stuff is always interesting to me.
</geek mode>