Let's say your list is called data, i.e.,
data = {{x1,y1, error y1}, {x2,y2,error y2}, ...}
then this will put it in the form you want
data /. {x_?NumberQ, y_?NumberQ, ey_?NumberQ} :> {{x, y}, ErrorBar[ey]}
Here's a test:
data = RandomReal[1, {5, 3}];
data /. {x_?NumberQ, y_?NumberQ, ey_?NumberQ} :> {{x, y}, ErrorBar[ey]}