OK! magazine's dramatically unspecific allegations yesterday that Larry Birkhead is not the upstanding, profoundly moral soul we'd expect an Anna Nicole Smith ex to be left us to speculate on our own about his torrid secrets. Now, TMZ dumps lighter fluid and a match on the smoldering coals with suspiciously well-timed rumors that MSNBC anchor Rita Cosby's dishy Anna Nicole tell-all — conveniently available Sept. 4! — claims Birkhead slipped Howard K. Stern something entirely different: