For those of you who don't know,
The New Jedi Order starts off 25 years after Return of the Jedi. Luke Skywalker has successfully started up the Jedi Academy (which is flourishing), Leia and Han are married and have three children. The older two (16-18 through the series I think) are Jaina and Jacen, the youngest is Anakin. Mara Skywalker (from some other books, as well as the Jedi Knight games I believe) is there too, and pregnant with the Skywalker's child (Ben).
The Yuzzhan Vong have invaded the galaxy by means unknown. They do not use technology as we know it, but use all biological technology, even their capital ships and fighters are organic. Oh yeah, and they don't show up in the Force.
Violence ensures, as the Vong capture world after world and the New Republic continues to ignore their presence. I won't give any specifics, but we'll just say that Courasant isn't what it used to be.