I dont think AMD cares at all about Itanic - leave alone positioning Opteron against it: Which position would that be?
Itanic? Is that anything like an Itanium 2? Name calling reveals far more negative about the one who does it than the object of derision.
As far as positioning, the modest FP performance and scarcity of major OEM support takes it out of running in the RISC replacement market. AMD tries to position it as a Xeon killer but AMD's precarious financial situation and lack of track record hinders it greatly.
According to a few individuals here Opteron is the gaming chip of choice for wealthy teenagers. That's probably the most credible positioning to achieve short term sales traction given the difficulties the chip faces but it may exacerbate AMD's image problem in IT.