SP1 has a great new feature. Deleted websites are moved to the site collection recylce bin.
But not all dialogs seem to be updated as you can see :
But .. the good news: it IS move to site collection recylce bin. NOT to the users recylce bin.
But … if you are going to delete the root site of your site collection the warnings are correct, except of the one sentence in the first warning;
A bit confusing, just look what you’re goíng to delete and always have a working backup!