I have always been of an opinion which tended towards that of Jackie and Father Steve, but I thought it would be instructive to see how M-W and the OED treat these. interestingly, this is one case where they agree in the main.
'orient' predates 'orientate' by about 100 years (ca. 1740 vs 1849). the original sense of the verb orient was to arrange to face to the east (they verbed the noun, which comes from the Latin word for east). from there the word has been generalized. (imagine that!) it seems that 'orientate' may NOT be a back-formation from 'orientation' (as I had also thought) but rather it was formed from the French orient-er in the same manner as some other English verbs [e.g., separate, create, isolate from separer, creer, isoler]. so it is completely parallel to orient in all of its senses and appears to have developed on a separate path!
