[speckledjim]

Colors tend to be used in programming quite a bit. I'd expect quite a lot of british programmers/techies tend to write grey, even though it's not how it's spelt here. Just as we techies often write 'color' instead of 'colour'.

[arethuza]

Grey is the UK spelling - gray is the American.

[christoph]

I use American English in programming and British English in normal writing.