Since the token appears to match the action icon on the pilot cards, and there is mention of and a reference card for new cloaking rules, I think it's a safe bet that it's a cloak token.

As for the Advance Cloaking upgrade card, it appears to be TIE Phantom exclusive. I'm willing to bet it has something to do with the TIE Phantom having a cloak legendary among cloaks. The cloaking action will probably start appearing on other ships (maybe even on old ships with new pilot cards), but this upgrade might be what allows the TIE Phantom to imitate its history of "almost literally undetectable in any way, until it fires, upon which it immediately cloaks again."

I suspect cloaking the Phantom will increase the agility to 5 or 6, cannot be target locked and cannot fire. The Phantom will still be able to be shot at, but the chance to hit and damage will be slim.

My thought for the Advanced Cloaking is that it will allow the Phantom to shoot while cloaked, but at an attack of base 2.

There is an auxiliary rules card for the 'cloak' action, and another extra card for the 'decloak' action, so I bet things are not going to be as simple as many proposed.

Who knows? Maybe you put the token on the table where the TIE cloaks, removing the miniature from the board. When the TIE decloaks, it 'appears' again at a given distance from the token...

Or maybe it is the token which moves around the battlefield...

I actually like this idea, it gives a true randomness.. maybe when you come out of cloak you set your ship within one range of the token, possibly in whatever direction you wish.. you can appear anywhere and with an advantageous position.. might be cool, or overpowered.. lol.. but an interesting idea..

It would be great if cloaking ditched target locks as well...

How about:

Cloak is taken before revealing manoeuver dial. Place Cloak token on the board on the rear nubs of the fighter. Do not reveal manoeuver dial. Remove the ship from the board. At the end of the next combat phase reveal your manoeuver dial and perform the manoeuver shown using the Cloak token to replace the ship. You may not perform a cloak and reveal a red or white manoeuver. You do not clear a stress token with a green manoeuver. Take a cloak cooldown token.

Cloak cooldown token - you may not cloak when you have a cloak cooldown token. After revealing your manoeuver during the manoeuver phase dial you may remove 1 cloak cooldown token.

Adv Cloaking allows you to cloak if you have 1 cloak cooldown token.

I can't wait !