This works:

int main(int argc, char *argv[]) {

    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
    int retVal = -1;
    @try {
        retVal = UIApplicationMain(argc, argv, nil, nil);
    }
    @catch (NSException* exception) {
        NSLog(@"Uncaught exception: %@", exception.description);
        NSLog(@"Stack trace: %@", [exception callStackSymbols]);
    }
    [pool release];
    return retVal;
}

For ARC:

int main(int argc, char *argv[]) {

    int retVal = -1;
    @autoreleasepool {
        @try {
            retVal = UIApplicationMain(argc, argv, nil, nil);
        }
        @catch (NSException* exception) {
            NSLog(@"Uncaught exception: %@", exception.description);
            NSLog(@"Stack trace: %@", [exception callStackSymbols]);
        }
    }
    return retVal;
}

Still waiting for some sort of explanation as to why the default dump no longer works and/or why (even more serious) uncaughtExceptionHandler doesn’t work. However, apparently this problem only affects the emulator.

update:

It has been pointed out that if you go to Product -> Scheme -> Edit Scheme, select “Run (Debug)”, select the “Diagnostics” tab, and click “Log Exceptions”, this will restore the missing Xcode default exception logging, possibly (I haven’t tried it yet) eliminating the need for the above hack.