Certainly. He doesn't have longevity yet, but the talent is potentially stratospheric. Look at the four stages of his single character in AMERICAN HISTORY X. More chameleonic than Hanks, more sober than Burton, and less weepy than Penn.
Well, we disagree. Hanks isn't a cameleon at all (well except for Forrest Gump). He is more like a Cary Grant. Loads of charisma and likability with enough acting chops to win you over no matter the role. Sean Penn is a chameleon. He played both Spicolli AND Harvey Milk, to perfection, not to mention a myriad of other roles. You may not like the guy -- he gets on my nerves too sometimes, but he is an extroidinary acting talent.
I saw American History X and liked it a lot. In fact, I like Norton. I just don't think he should be ranked ahead of such accomplished actors (including Richard Burton). They are multiple Oscar nominees and winners.
I always felt Norton had "potential" to be great too, but so far, he has seemed to reach a plateau and that plateau isn't on Hanks, Burton, and Penn's levels. It makes me think that Norton has talent, just not enough to place him among the all time greats.