X20:
http://www.dpreview.com/previews/fujifilm-x20
The X20 is an improved version of the X10 with a 12MP X-Trans II sensor which has on-chip phase detection AF and a optical viewfinder with a LCD overlay.
The sensor also lacks a low pass filter too.
X100S:
http://www.dpreview.com/previews/fujifilm-x100s
This update to the X100 introduces the 16MP X-Trans II sensor which has on-chip phase detection AF too.