Rechargeable batteries (as in lithium-ion type?!), "lit display" (backlit?!), and foldy. Feb 14th in Japan, March in EU and NA. ~$100 too.
Looks positively fugly to me, but I guess its nice and more 'pocket' friendly. I hope its backlit.. even then, the only thing for me that can save the GBA from being Steel Batallion trade-fodder is FF IV, V, VI
Ah well, I'm sure someone's bound to love it.