Should IBOutlets be strong or weak under ARC?

I am developing exclusively for iOS 5 using ARC. Should IBOutlets to UIViews (and subclasses) be strong or weak?

The following:

@property (nonatomic, weak) IBOutlet UIButton *button;

Would get rid of all of this:

- (void)viewDidUnload
{
    // ...
    self.button = nil;
    // ...
}

Are there any problems doing this? The templates are using strong as are the automatically generated properties created when connecting directly to the header from the ‘Interface Builder’ editor, but why? The UIViewController already has a strong reference to its view which retains its subviews.