Radio waves go in multiple directions, lasers can only work in short range, unless you find a superb trick to keep the alignment perfect at great distances.
What is different is that you have to know the relative proper motion of the target, since you have to "lead" the target just like you do when skeet shooting. I don't know whether the lead angle is significant, but proper motions of nearby stars have been measured (e.g. by Hipparcos http://en.wikipedia.org/wiki/Hipparcos) and calculating the resulting lead angle isn't difficult.