Did it predate the 8008 or come later?
A little poking around on Google suggests that the 4004 and 8008 came before the 4040, and that the 8080 came after the 4040. Another entry suggests that the 8080 may have been a "sibling" of the 4040 in terms of time. Clearly the 8080 and 4040 were offspring of the 4004 and 8008, respectively.
I never worked with any Intel 4-bit processor. Was the 4004 the one that Intel designed to make a calculator? The 4004 and 4040 look like they were designed to do BCD math.
There are numerous listings on Ebay for 4040 processors and surrounding parts.
It would probably run faster than that SHA algorithm that guy implemented for an IBM 1401 computer (1960's vintage).