Wes Benedict has it exactly right. The best strategy for the LP over the next couple decades is to try to act something like a trim tab (non-pilots look it up) on the vast political forces marshaled by the incumbent nanny-state parties. When I try to write a scenario in which American liberty is increased on the strength of votes cast by LP legislators, it sounds like science fiction: http://knowinghumans.net/2006/07/resigning-from-libertarian-party.html. We should have libertarians working both within those nanny-state parties and within the LP, to maximize the attention those parties give to the opportunity cost the LP makes them pay. To maximize the size of the opportunity cost itself, we need to 1) work with other third parties on electoral reform, and 2) cure the LP of the brain damage that makes it reject fusion candidacies or any other possibility of supporting the most freedom-increasing ballot choice when that choice is labeled with a donkey or elephant instead of a torch lady.
Brad Spangler (like Charles Johnson a month ago) is also right to say that anarchist state-haters don't have very good rebuttals available to radical arguments against working within the LP or any other political party. The only way I can see for a principled hater of state force-initiation to work within the LP is to take and advocate something like this pledge: http://libertarianmajority.net/no-1st-force-pledge.
However, Spangler is wrong in trying to identify "real libertarianism" with zero-aggression absolutism. There are too many free variables in libertarian ethical theory, and too many different principled schools of libertarianism, for this ploy to work on anybody whose knowledge of political and economic theory goes much beyond the LP's pledge and its interpretation in the echo chamber of LP radicals. For all the details, see http://libertarianmajority.net/#Advocacy.
Oh, and Spangler's argument for the dissolution of the LP would be less unpersuasive if he knew a little bit more about the Party. Contra Spangler, it doesn't take a 7/8 vote to amend Bylaws Article 2 regarding the perpetual duration of the Party. It just takes a 2/3 vote on an amendment that is properly noticed.