As has been previously announced OLPC is planning on moving to an ARM processor to advance the XO platform. The major advantage is similar computing power while having a massive reduction in power usage so as to maximise runtime.
Chris Ball has just posted a XO 1.75 status update to the Fedora OLPC list to let us all know that the project is moving forward and by the end of a recent bringup event the board is now booting a linux kernel and what is presumably a hacked up version of Fedora 12. YAY!