There is something in your application code that is leaking. The UIApplicationMain function is the entry point of the stack trace, if you follow the calls down into your application code, that is where you will find the leak.
If you can identify the method that seems to be leaking, you can post that code, and someone might be able to help more.
Start with the basics. Make sure that you are releasing all of your UI controls and business objects in the first object that is loaded. Make sure all resources during initalizition is properly released and then ensure you are instating things correctly. Are you using the pattern like?:
UIButton *btn = [[UIButton alloc] init]; //not really complete...
myObj.myButton = btn;
[btn release]
Finnally if nothing else step though the code in your mind and identify when something is being alloc and then identify the exact point that it is being released. If you can't identify where the release is, you've probably found your memory leak. Find a solution and retest. It make take a while to identify every leak. I always assume that there are multiple sources until they or it is resolved.
Like Andy mentions, if you need more direct help you are going to need to post more code.
Are you running the tools on the device or the simulator? I've found that memory issues can be different between the two.