It's been leaked somewhere (I can't remember where), and there was another article in which someone who apparently knew one of the script-writers gave some info on the plot - it may not be true, of course, but I thought I might as well put it here.
The films will revolve around Jaina and Jacen Solo - they'll both be great Jedi, then
Jacen will go dark-side.
I've heard no mention of Anakin Solo though.
That's it, in a nutshell.