Next step: convince everyone to use your weekend project, instead of Twitter. Allowing people to import all of their tweets and friends would be helpful, so be sure to implement that.
Next next step: Handle all of Twitter's traffic. Consistently, and you not only have to do it better than they did in the beginning, but better than they do it now.
It is a big problem and not just from an engineering standpoint. The same for facebook.
On the plus side, for competition at least, as hardware technology advances it'll become easier and cheaper to match twitter's capabilities with less effort.
http://www.google.com/patents?q=Twitter&btnG=Search+Pate...
Although they did make Loren Brichter patent "pull to refresh":
http://www.google.com/patents?q=Loren+Brichter&btnG=Sear...
Also, please don’t be "I could clone that in a weekend" guy. Everyone hates that guy.
http://blog.bitquabit.com/2009/07/01/one-which-i-call-out-ha...
You could make a piece of crap implementing Twitter’s models and create/read/update/delete in a weekend. Or really, in under an hour with Rails scaffolding. Congratulations, you have now proved that you can guess the schema from using an app. You don’t have a product, or even one tenth of a product.
First-past-the-post has nothing to do with Twitter’s success; polish and thought and sweating the details has everything to do with it.
Back to the topic, three months ago someone went ahead and pulled off a high-performance (no sure its scalability) Twitter clone in C. I recalled it's a good discussion on such a topic.
Discussion can be found on Reddit: http://www.reddit.com/comments/f16mw/ive_never_been_impresse...
Its website is at http://blerg.dominionofawesome.com/
EDIT: moved "heavily qualified" to something more idiomatic.
But there's so much more that makes it more than just a technical problem. Ask your random 40-year-old working in a non-tech industry if they've heard of Twitter. Now ask them if they've heard of StatusNet or identi.ca.
In a nutshell, that is what makes it more than just a technical problem.
I don't know why your other post was downvoted, but probably because people think it's not an interesting question, could be determined by actually going to Google yourself and doing your own homework/search and most people don't feel like patents, if they exist, are the problem with twitter's dominance.
Also, your comments contribute what to this discussion?