Is it any surprise that iTunes is now the largest online music store in the US?

Last week, Apple officially confirmed that they have overtook Wal-Mart, having sold over four billion songs since its launch less than five years ago.

And with Apple adding more features to iTunes like movies, podcasts, and maybe games in the future, it looks set to become perhaps the largest multimedia store too. 

Now the challenge is to make the store available to as many markets as possible. Currently, only users from 23 countries can buy content from it.

The main barrier seems to be piracy, which is rampant in asian countries like China. In Japan, some labels have held back selling songs through iTunes due to fear of piracy.

In the mean time, the future looks bright for Apple. And with new iPods in the making and a new iPhone coming in June, we can only foresee a greater lead for iTunes.