So it is my understanding that with the introduction of Black and White, before each battle you see the opponents party, and are then able to switch which pokemon is in the 1st slot (your lead). In my opinion this renders dedicated Lead Pokemon such as Suicide Leads and Anti-Leads completely useless. In fact I would go as far to say that the concept that in a team you should have a dedicated lead is obsolete.
And yet in the Competitive Rate My Team section a majority of teams being posted still contain a lead Pokemon, which got me to wondering that either 1: People don't even know about this new feature. Or 2: That they believe that a lead pokemon is still a viable and good option.
Now here's my two cents: Having a dedicated lead is not useful
Explanation: Being that you are able to view your opponents team and are able to rearrange your own team to suit means that you can get a fair idea of that teams weaknesses or perhaps that teams overall strategy.
Eg: If you see a Tyranitar and an Excadrill, it is fair to assume that your opponent is planning a sweep with Excadrill, in doing this you may not want to lead with your Gliscor (a common lead) as you might not want to risk it getting fainted, as Gliscor is a great Excadrill counter, and you want to keep Gliscor in the battle to be able to prevent being swept by Excadrill.
So in my opinion, it is beneficial to not have a pokemon that you will lead with EVERY time, as this prior-view allows you to plan your battle rather than just sending out a pokemon because it is your lead.
So there it is, I'd very much like everyone else's opinion on this too though, but PLEASE before you post, read the whole thing! I took the time to write it, so it'd be common courtesy if you would take the time just to read it.