all your paid apps that you have will sync to your google account. When you get the new phone they should resync back up if they don't for some reason they will be available in the market downloads section. Your free apps will have to be downloaded again though.
Also, for not rooted people, my backup pro will help automate reinstallation of your apps. Google will keep track of all the apps you bought and MOST of he free ones downloaded, but sometimes it looses the free ones. and redownloading everything is a bit slow. This is where my backup pro can help. Its much quicker to reinstall apps. The only downside is that it doesn't backup the data within most apps.