Well there are two things going on here:
According to Talmudic law, upon hearing bad news, one is supposed to say:
Baruch ata adonoi eloheinu melech ha'olam, dayan ha'emes.
Blessed are you G-d, our Lord, king of the Universe, the judge of truth.
Now what constitutes "bad news"? Certainly a death in the family, but all sorts of other things could be bad news depending on your situation. Learning that your investments went up in smoke, for instance. (There were situations when upon hearing that one's ox died suddenly, the blessing was made. Not out of grief for the loss of a pet, but because that was a serious piece of business capital.)
I'd thus assume that if someone was stricken by a non-Jew's death sufficiently to call it bad news, s/he should acknowledge G-d's judgment accordingly. There aren't hard-and-fast rules here, it can depend how you feel. I'd assume if a convert stayed close with his/her non-Jewish parent and the parent died suddenly, it would be bad news and thus appropriate to say the blessing.
So I guess the question really is, how deeply and personally do you feel the sudden news of Steve Jobs' death? My guess is that for most people it doesn't quite hit the bar, but that's just me. (Of course, how much Apple stock you own could make a big difference here ...)
The other question is that we're accustomed to saying "baruch dayan emes", "bless the true judge" as a shorthand (without the name of G-d), whenever we share bad news. This is more of a cultural question; my impression is it's usually used either for a notable Jew ("baruch dayan emes, Rabbi Menashe Klein passed away just before Rosh Hashana") or for something particularly personal ("baruch dayan emes", my neighbor the convert just lost his parents in a car crash). I'd beware its dilution by using it for any death one hears of; not as a matter of law but as a matter of taste.