There are at least 4 bugs involving brick placement.
1. When bricks are created very far away from you, you see them as being a few thousand units in the wrong place. When a brick is placed directly on top of another brick, both bricks will disappear because of the hidden surface removal code. This is demonstrated in Spaceomega's save and is now fixed (Thanks)
2. A rounding error causes the position of a brick to appear off by 1 plate height. This is what StoreClerk is talking about. Saves will not work to repeat this bug because the bricks will actually be saved in the wrong position. If you have a method for recreating this I would be very interested.
3. Traveling at extremely high speeds causes bricks to be scoped to you, but by the time they send their position to you, you're too far away and they end up in the wrong place. Similar to bug 1.
4. The oct tree gets confused sometimes and you end up with bits of geometry (and sometimes whole buildings) appearing in 2 places at the same time. Usually really far apart