Borderlands Phase Strike Skill Broken

MTV Multiplayer reveals that the top tier of the Siren skill tree is broken, as the powerful skill Phase Strike is not doing near the damage it should.
Phase Strike sits at the top of the Siren's Assassin Tree and, when maxed, is supposed to dish out 800% melee damage when meleeing during a Phase Walk. Last night my second major character, a Siren, reached level 25 and I was finally starting to dump serious points into Phase Strike, thinking that I could basically one-shot a single enemy with rogue-like backstab. It wasn't to be. Even fully maxed, Phase Strike won't deal much more than a normal melee attack, let alone 8 times that amount.
MTV Multiplayer also informs us Gearbox is aware of the bug, so hopefully a fix is forthcoming.
"We've been doing some investigation into Phase Strike, and it does not appear to be working as intended."