You don't notice any of its performance increase over a 4870 either, unless you go SLI. So unless your like Nosboost or Veedub, then there really is no reason to go GTX 260. That is, if your after price/performance without plans to SLI.
Maybe I don't see the point in going SLI with a 300$ Graphics Card, but if thats what rocks your boat. Then by all means go for it.