P 57 includes no text about power-use secrecy, except to say that a creature gets to know exactly what you've done to it. It includes zero text saying that it doesn't get to know that you've used the Use a Power action. According to the DMG, you're assumed to be open and above the board about the sorts of actions you're performing.
For example: You don't have to tell them the creature -has- an unused interrupt action, but when the creature performs it, you're supposed to let them know what the action does, for the most part. When you're using an action, you're supposed to let them know what action you're using, even if the specifics are kept quiet.
The sequence goes like this.
Ranger declares he's using the Use a Power action, no target.
Kobold knows he's using a power, knows he's not target, and through free action use, knows his fellow allies are not targets.
Ranger shifts.
Kobold reasonable deduces the shift is part of the effect of the power, and can decide as a matter of tactics whether or not it is wise to shift again. Now, he doesn't know if the power is 'Shift 5 squares' or 'Shift two squares' but he knows a) it's a power and b) it's a shift power. He might conclude the character has a shift X power, or might also conclude the character has Shifty. It's very reasonable for members of a race who have a power allowing them to shift acknowledge the existance of powers that allow the user to shift.
Yes, this also means that players get to know that Kobolds use a power to shift 1. It works both ways.