The $200 instant rebate for the Nikon D800 will expire this weekend (May 31st) and it will not be extended in June. It seems that Nikon USA is happy with the current D800 inventory/sales before the rumored replacement is announced in the summer. This may be your last chance to get a D800 body for $2,796.95. Note that you do not have to purchase any lenses in order to get this $200 instant rebate.
Regarding the current Nikon body + lens combo rebates: they will be extended and more lenses will be added in the selection. I will post the details once they become available this weekend.