The following class generates a NullDereference warning:

@interface TestAssert : NSObject {
	
}

@end

@implementation TestAssert

- (id)initWithPointer: (int*)x
{
	NSParameterAssert( x != nil );
	NSAssert( x != nil, @"" );
	
	if( (self = [super init]) != nil )
	{
		*x = 1;
	}
	
	return self;
}

@end

Although the checker seems to understand assert(), both NSAssert() and NSParameterAssert() are ignored, causing false positives like the above. Maybe this falls under inter-procedure checking, but given that assert() fails to trigger the above warning, I'm suspecting it is it's own special case.