In British English, I know program is usually used instead of programme when dealing with computers, but I wondered whether there are other things for which program is generally used instead. Is there any particular reason why the American version of the spelling is sometimes used?
I think it's just down to the dominance of AE in the field, with possibly a preference for simplicity and clarity among programmers, etc. Or maybe they just can't spell in English. I searched the British National Corpus ([DAVIES] Variation in English Words and Phrases (VIEW)) and the vast majority of example were computing or American English.
When Tdol refers to 'the dominance of AE in the field' - meaning IT - I'd add that this could apply to other fields too. Many motivational self-help books and management books tend to favour the AmE spelling - also personnel departments (at least, the ones that call themselves "HR departments" - Human Resources). I imagine this caveat covers most of the exceptions you find in the BNC.