PSC/MMI also has a K-27 arriving any day now. They are also announcing 8 other locomotives available for reservations, including 2-8-0s, 2-8-2s, 0-6-0, and 4-4-0. See
http://psc1.virtualfocus.com/ for details. Don't know for sure how many or when all these will actually be produced, but I'm reserving a 4-4-0 in hopes.
Blackstone is producing a new box car and stock car that should be available this summer. See
http://www.blackstonemodels.com/products.htm.
MicroTrains has a new release of an HOn3 car about every other month.
All the above are RTR. There are still many car and structure kit available, with new ones being released frequently.