And *that* is how to reverse a linked list. I'm an idiot for messing this up.

gistfile1.pyw

class Node(object):
    def __init__(self, value):
        self.value = value
        self.next = None
    
    def __str__(self):
        """Return a string representation of the list starting here."""
        values = []
        curr = self
        while curr is not None:
            print repr(curr)
            values.append(str(curr.value))
            curr = curr.next
        return ",".join(values)

def reverse(head):
    """reverse a linked list in-place and return the new head."""
    curr = head.next
    prev = head
    prev.next = None # Break the link between the head and whatever's after it.
    while curr is not None:
        # Retain a reference to whatever curr points to now.
        tmp = curr.next
        # make curr point at the thing before it.
        curr.next = prev
        # move everybody forward.
        prev = curr
        curr = tmp

    # when this loop terminates curr should be None but prev
    # will be the last element, now the first.
    return prev

if __name__ == "__main__":
    # Some demo code.
    a = Node(4)
    a.next = Node(5)
    a.next.next = Node(6)
    a.next.next.next = Node(7)
    print a
    b = reverse(a)
    print b