From
clubjade.net, some mild spoilers for the upcoming Invincible novel:
"Luke Skywalker is stuck on the horns of a dilemma. He is convinced that Darth Caedus, the Sith Lord who began life as Luke’s own peace-loving nephew, Jacen Solo, must be destroyed-yet he worries that his vision is tainted by his own anger, pain, and desire for revenge. Jaina Solo, Jacen’s twin sister, has completed her training under the galaxy’s most fierce anti-Jedi warrior, and now it falls to her to fulfill her destiny as “Sword of the Jedi.” And so while the forces of the shattered Galactic Alliance struggle to end the civil war that has set planet against planet, Jaina-along with her parents, Han and Leia, fellow Jedi Knight Zekk, and old friend Jag-heads right into the lion’s den to confront the horrific tyrant who was once her twin brother…."
Invincible is the last book in The Legacy of the Force series and will be released June 3, 2008. I'm very interested in seeing how they could possibly wrap up this series to the satisfaction of the readers...and even if that's attempted.
*UPDATE: The release date of Invincible in the US is May 13.