The errata for Complete Adventurer's skirmish ability states the following
She deals an extra 1d6 points of damage on all attacks she makes during any round in which she moves at least 10 feet away from where she was at the start of her turn. The extra damage applies only to attacks made after the scout has moved at least 10 feet. The skirmish ability cannot be used while mounted.
I have a discussion with my DM at this time for this unclear way of determining what "away" represents. As the sentence is "during any round in which she moves at least 10 feet away", I understand that the distance away has to be calculated from your point of origin to your point of arrival through a path you can actually move. For instance, someone with Improved Skirmish feat, would require a 20' "move away" distance. If the Scout is moving through a 5' wide corridor, 10' North and 10' East, he would have moves 20' and would be 20' away from his origin. My DM states that it should be understood that the distance is in straight line, thus my last example would deny the skirmish ability to the scout who has turned a corner as the "flight" distance would be about 14' not 20'.
So, as written, when determining a move distance, would you use the path that you can physically use or the straight line kind of approach?
Another example, if there is a closed door to a room on the East side and an opened entrance on the South side and you use your move action to move around and end up 10' from your point of origin in the room, would you get your Improved Skirmish feat kick in for your standard action attack? Of course if you open the door this round, next round you would have to calculate the distance through the door as it is physically possible.