For several years, top Ping players like Bubba Watson and Louis Oosthuizen, among others, have been playing the company's S55 blade, with pretty impressive results. Based on a sighting at TPC Sawgrass, however, it looks like they might be switching to a new model in the near future.
Called iBlade, the new design is clearly the replacement for the existing S55, and while company reps haven't released any information yet by comparing images of the two clubheads you can see a few changes: the cavity appears larger in the iBlade and doesn't feature a stabilizing bar. This likely will move more weight lower in the clubhead and to the perimeter, making the new model somewhat more forgiving.
In addition, the tuning port, which is used both to customize swingweight and to reduce vibration, also appears to be bigger in the new model. It is possible that this will make the new model feel even softer than the S55.