Don't know if it was fixed or if, when we tried it with pinkie we were looking at the wrong stuff.
http://www.swtor.com/community/showthread.php?t=585245

Important bits:

XGBox wrote:

With these numbers, I can conclude that the enemy attacker will first have its damage reduced by 5%, then split in half as two attacks between the two players. Each player uses their individual damage mitigation resources (e.g. armor, cooldowns) to absorb the resulting split damage. Each attack has its own chance to critical but will only calculate its own split damage.

XGBox wrote:

The last three shots indicate that some form of shield/absorb chance may be in effect. We can see that the targeted player takes normal damage but the damage to the tank is almost halved. This would lead me to believe that shield and absorb does work, counter to my previous statement, but it will not indicate it as being successfully shielded or absorbed anywhere in the game. This is proven as shielding Guard damage does not reduce charges of Dark Ward.

I can also confirm that Defense chance will be calculated through Guard damage so long as the originating damage could've been mitigated (i.e. Melee/Ranged but not Force/Tech). You can easily prove this by dealing damage to the targeted player and see that, occasionally, damage towards the tank will not be applied at all. One caveat: This will not show up on a parser, and you will not see text indicating that you have dodged a guarded attack.

Essentially guard works. Damage transferred to a tank will get DR and may also be affected by D/A/S. There will not be any animation or fly text though, but the numbers will go through the equations.