Aperture raw support comes as a downloaded sw update to basic camera raw support that is used by other apps like iPhoto. LR support on the other hand is not depended on the apple camera raw sw, instead they use their own camera raw sw module which is used on all their products.
Adobe tends to update their raw sw sooner then apple does though. There is also adobe dng converter, but the dng files are not fully supported by apple due to multiple dng types and apple currently only supports one type, if I remember correctly.
Gary
Ps. Go check the adobe website on xt1 raw. I think there is a rc candidate that supports xt1.