Originally Posted by Roze

Rooting gives you super user access to your phone. You have the same control as an Administrator on a computer. You have the ability to uninstall stock apps you don't want. You can overclock the CPU for faster processing power or underclock it to increase battery life. Where rooting shine is that you have the ability to load custom ROMs. I've read that there are a few custom ROMs that will include the market app. Please be careful with rooting as it will void your warranty. Do as much research as you can before you root and flash custom ROMs.

If you want to know more, you can read the posts in the root forum: X10 - All Things Root - Android Forums