Yes, she does look like Kairi, but she also looks like Namine and has the vioce of Aqua. Maybe these are all related?
I do think she could be a darker part of Kairi. Like
Kairi = Light
Namine = Twilight
Xion = Darkness
A bit like with the trios. (I say Trs because there seems to be a trio relationship with Xion, Axel and Roxas.)
talking about trios... There is definatly some.. resembalence with The Axel group as wit the sora group. I.E...
I currently own all three 3rd gens. But I dont think it bloody matters if it comes out on 360 or PS3.
There HAVE been reports of it possibly being multi platform ANYWAY. Not just PS3