Saw this on kiteforum.com Looks like they worked out the issues of the bladders and valves.
I also like the way they removed the center strut. Should be a lot cleaner air flow. Just have to pump up one extra strut now.
Not a big fan of the new color scheme but I would still test one out.
http://www.ionfour.com/Ion4_PL_2009_lowres.pdf