Ghost touch gauntlets and shadow projection can

[Rogar Stonebow]

You grapple?

[Kazaan]

Are you asking whether a person with GT gauntlets who casts SP can use their shadow to grapple corporeal creatures? Your shadow would basically have to take the gauntlets off your body but GT weapons can be picked up and wielded by incorporeal creatures, however nothing indicates they interact with the Grapple maneuver. You need more than just your hands in order to grapple; it isn't as simple as just grabbing their wrist with your hand(s) only. To put it simply, Grapple doesn't utilize a weapon like Trip, Disarm, or Sunder so you gain no benefit from any enhancement bonus or special ability on the weapon. You could use your GT gauntlets to Sunder, Trip, or Disarm, or to punch, but not for grapple, bull rush, or even dirty trick, by RAW.

[Emmanuel Nouvellon-Pugh]

What about weapons that explicitly have the grapple ability, for example the man-catcher from APG?

[Kazaan]

Grapple weapons would be an exception to the rule since they explicitly are designed for grappling. At the very least, I'd say the free grapple you get from a critical with such a weapon counts the weapon's special properties and it could be argued that such a weapon can be applied to a normal grapple attempt as well. So a Shadow Projection wielding a Ghost Touch Man-catcher would be pretty interesting; just keep in mind that while the shadow may be incorporeal and capable of phasing through walls, the weapon still counts as corporeal so you'd have a very funny scene where your shadow tries walking through a wall, door, or other solid object and the weapon is "stuck" or just falls to the flood with a clatter.