Twitter has been on the fastest growing companies in terms of its rapid rise in web hits. In fact, so rapid that it now ranks just above Digg, according to Hitwise.

But could this be temporary? Twitter got a lot of attention from the Hudson River plane crash – boosting not only it’s brand, but traffic as well. Further, it has got more attention from the recent Presidential Inauguration and I’m sure many such events where media will refer to Twitter’s user status.

So with all this traffic – it’s no wonder that Twitter displaces Digg. However, does that mean that Twitter makes more cash? Well, not really.

Digg has ads and they earn revenue from that, however Twitter on the other hand isn’t ad-supported but instead plans to have premium services. Like a premium account, or paying for a valid verification as a celebrity or corporate member. Hence, Twitter will not be dependent on traffic count, but instead measure itself by growth of user registration.

Now, if you look at the graph below issued by Hitwise on a comparison between Digg and Twitter – you see that there is an increasing volume to the point that Twitter has caught up.

However, I figure that the traffic for Twitter mostly represents new users. This is on my assumption that most existing users use third party apps or mobiles to update their twitter status. Hence, that being so, we see a potential growth of Twitter’s user base. Therefore, I assume that the user-sign up graph would be in a very similar pattern to it’s increasing web traffic.

Question is – how many of those will pay for a premium account? I can’t see Twitter putting ads anytime soon – and if so, revenue from that could be minimal if most users are using various other ad-free means to update their status.