The sales of Mini 12 netbooks has been stopped by Dell. This is due to customer demand.
An explanation was posted in a blog post about the decision which says:
It really boils down to this: for a lot of customers, 10-inch displays are the sweet spot for netbooks. That’s why we offer two different 10-inch Inspiron netbooks for Mini 10 and the Mini 10v. And on the Latitude side, the Latitude 2100 netbook is finding a home in schools all over the place.