From the Jedi Academy rule sheet:
Targeting: Once per turn on its turn, this character can choose an enemy within line of sight, following all the usual targeting rules. The target has -4 Defense until the end of the round. It doesn't take any time to use Targeting: the character can still move and attack normally this turn.

Once per turn on its turn - can only happen on its turn obviously but once per turn? does not replace attack nor does it happen at the end of the characters turn like override. then when?
Ok it has to follow the targeting rules but "it doesn't take any time to use" which would imply that it could be used at the instant when it is moving from one square to another - ie move 3 squares, line of sight, legal target, enemy has -4 Defense, move 9 squares and hide.
Since it can "move normally this turn" - speed or double speed without attacking - not that R4 or the treadwell can attack!
Also the statement "until the end of the round" not until the end of the round or this character is defeated.
Who makes the final call now that Wizards is shut down??
I seem to be a VERY powerful ability in the above context and it either needs to be edited or explained.

Also to note: Zero-time abilities/force powers can't be used in conjunction with (Greater) Mobile Attack, as those abilities only allow you to make an attack or a "replaces attacks" force power/special ability in between movement and zero-time abilities are neither.

This is in the FAQ, but in a bit of an odd spot. It's under the general questions section of the "Force Powers and Force Points" category (as the first zero time things were Force Powers like Transfer Essence and Force Stun).