This is really strange. At the career fair at my school, the USPTO was there recruiting engineers and CS students. Assuming one single person with even a modicum of programming knowledge looked at this application, I can't see any way that this was issued, let alone after 4 years of sitting in purgatory(?). If this was sold to Lodsys could they sue any company that used a doubly linked list without licensing it? How would they even find out about what data structures you used in your code?