Quote Originally Posted by uhicha neji
2 Sharingan users in the same organization That seems like laziness on part of Kishi... I for one am not pleased that Tobi seems to be apart of the Uchiha clan :\

I hope those are false.
Yeah...laziness. These events are probably one of the most thought-out plot elements in all of shippuuden. Obviously, Tobi isn't part of the organization just to be an akatsuki member. Considering his interest in Sasuke, I'd guess that he joined because of Itachi.