well, you might be able to trick some one into flipping out. have four-five light frigates at once came at a planet from multiple phase lanes, and have your fleet attack elsewhere. your opponet should see the alert on the screen, but it would show the diversion planet, not the true target planet. only if he/she went into the report menu would they see it. might work, might not. also, will not work with scouts! they do not ring the audible alarm.
another idea is a simple scout rush. this is precisely because they don't ring the alarm when sensed incoming, and would be able to move close to the enemy's planet with near impunity, drop some charges, and leave without firing a single gun (then the "our planet is under attack" alarm would sound. don't know if it sounds for abilities, tho