Stross, Charles
The Revolution Business
9/23/11
5 of Merchant Princes series
Niejwein (midieval) is fighting - world walkers vs. Prince Egon.  New Britain (20's era) is fighting - proletariat vs aristocracy, world walkers not involved.  The US decides to take the fight to the world walkers in Niejwein by exploding a nuclear device there but manage to kill off Egon and his followers instead of the world walkers.  Mariam/Helge begins to take up her role as Queen of Niejwein working with her mother.  She is pregnant with the heir.

Jance, J. A.
Kiss of the Bees
9/25/11
2 of Walker Family series
Andrew Carlisle has trained a disciple to carry out revenge against Diana Ladd Walker through her adopted daughter, Lani.  The disciple is another psychotic killer who wants his own revenge against Brandon Walker, Diana's second husband, who put him in jail.  Right prevails and the intermixing of Anglo and Indian culture in Arizona is interesting.

Stross, Charles
The Trade of Queenes
6 and last of Merchant Princes series
9//11
The US having discovered Niejwein world, blames the whole continent for the actions of a disident minority and decides to nuke it back to the stone age -- not so far to go.  The dissidents return the favor and nuke the White House, the Pentagon.  So the World walker clans decide to move to the New Britain world which is staging the French revolution in the US against the British monarchy.  They buy their way in by importing modern technical information.

Aguirre, Ann
Aftermath
5 and last Sirantha Jax
9//11
This is one of the best series closers I have ever read.  Sirantha spends most of the book paying for her previous actions and trying to right wrongs she feels responsible for.  Her lover March is elsewhere righting his own wrongs.  The character's story is deepened by backfill.  And the ending is just right.