An eloquent editorial in the LA Times suggests that the answer is yes. Put it this way: What would our reaction be if it were discovered that someone held by the Taliban were being subjected to the treatment apparently imposed on Pfc. Bradley Manning? Is this just another example, alas, of the maxim, "if we do it--and it doesn't include the rack and screw or waterboarding (for the Obama Administration)--then it isn't torture" (or even "cruel, inhumane, or degrading treatment"?)
For better or worse, I can't blame this on the Constitution, which, properly interpreted, would find such treatment to violate the 8th and/or 14th Amendments. (In the Orwellian world of the law, the 8th Amendment might not apply because Pfc. Manning's treatment isn't "punishment" after conviction (which is what is presumably covered by the Amendment), so we have to turn to an "unenumerated right" contained within the "privileges or immunities of US citizenship."