In one of the final chapters of volume 29 (the manga), Naraku demands that an old youkai tell him where the final jewel shard is. He then says that the shard can be found in between the real world and the spiritual world. In other words, you have to be dead to get it! Does that ring any bells? My best guess is that Kikyo could get this jewel shard...if it weren't for the fact that Naraku "killed" her (pushed her down a huge crack in the ground) in an earlier chapter! My best guess is that she'll soon come back, as she did in the volume where she was resurected (I forgot which one ^_^")and took a nasty plunge down a waterfall.
Submitted by SIT BOY!