Nikon D4 and D800 Rumors Continue

Something must be cooking with all of the “new Nikon” rumors slating cameras for late-Summer.  The most recent rumor comes from Nikon shooter Bryan Peterson, who is know by many for his great Understanding Exposure books.
Peterson posted on his Facebook account that he has an inside friend in the know, and that a pair of new Nikon full frame cameras will be announced by the end of September:

Two new Nikon’s-The D800, at 20MP, full frame, retail price of $2495.00 and Nikon DX-4, full frame at 19-20MP with a retail price of $5,000.00 and both will be announced by late September 2011!

Peterson went out of his way to assure his followers that this info is legit and that he’s never been on the rumor bandwagon before.  I can only assume that the “DX-4″ reference is a typo since “DX” is a designation for Nikon’s APS-C format lenses and sensors.
A Nikon D4 and D800 coming out side-by-side seems like a rather odd move considering that the D700 launched roughly nine months after the D3.  Also, he didn’t mention the Nikon D400, which has previously been rumored to launch in August.
What do you the full frame users think about a dual launch of the D4 and D800?  What would make you purchase the D4 over the D800 (or vice versa)?
[via Nikon Rumors]