Well, we've just blown the doors of of the previous "record" for oldest family photo. Perviously it had been of Lydia Richardson (b. 1832). This one is of Jonathan Waterbury (b. 1766 d. 1825) and Sarah "Sally" Travis (b. 1770 d. 1857). Its from a book called Jonathan Waterbury Genealogy. At the page facing 128, there is this photo:
Quite a handsome couple, eh? Old as it is, though, it still doesn't predate the photo of my wife's 6th Great Grandmother, Rebecca Machado.