ah, the smug eliteism in this thread...you guys do realise that your just one quarter of the group right? being a tank does not make you an almigthy god with rights to decide who gets to stay. hate elitist jerks like you guys.
It's hard not to read all these posts and not think of people leaning back in their chairs smoking a pipe isn't it? But, in all honesty, the tank really is the default leader in a PUG. Coming from someone who mainly heals, the tank really needs to dictate the pace since he (should) be the one jumping in first and pulling aggro, etc. Granted, being the 'leader' doesn't mean pulling the 'my way or the highway' card, since then you are just being a dick about it. The only times a tank shouldn't be leading is when you actually know the people you're with or you trust someone who has possibly done the FP/HM or whatever a few times and you are still learning specific things. Other than that, tank is leader.