Multiple sources have confirmed that dual-core Atom won't make it to netbooks at least until Q3 2009. There is a lot of pressure from big names, as they would like to release and sell dual-core Atom based netbooks, but Intel thinks releasing such a product could endanger its average selling prices of existing notebook CPUs.
AMD will release its dual core sub-20W platform in mid-2009 and it wouldn't surprise us if Intel suddenly changes its mind and releases dual-cores for netbooks. You can buy a decent notebook with a dual core for around $500, and this is already rather low.
Dual-core Atoms will get to netbooks, but not until Q3 2009.