According to Tom's Hardware, a Chinese e-tailer site briefly carried a listing of the upcoming Intel 10th gen Comet Lake-S desktop CPUs qualifying samples (QS) for sale indicating that we may not have to wait much longer before retail units become available. Another managed to get its paws on a Core i9-10900.
Comet Lake-H and Comet Lake-S series are expected as early as March 2020 to possibly counter AMD's advances in desktop and mobile.
The 10th gen Comet Lake-S chips were noticed on a Chinese e-tailer site named Taobao. The sample specification (sSpec) number on these chips indicates that these are actually qualifying samples (QS) that are seeded to OEMs and ISVs.
The now-removed Taobao page listed five Comet Lake-S processors: Core i5-10400, Core i5-10500, and Core i5-10600K all of which are 6-core 12-thread parts. With the exception of the Core i5-10600K, which is rated at 95W, the rest have a 65W TDP. The seller seems to have stocked the Core i9-10900 and the Core i9-10900K too.
Owning the actual chip might be a bit pointless. The Comet Lake-S needs a new motherboards with an LGA 1200 socket and a 400-series chipset such as the Z490 or the B460 and these have not been seen yet.
Chinese news site XFastest appeared to be playing with a Core i9-10900 chip. It is not known whether they purchased it from Taobao or Intel sent them a sample. The Core i9-10900 has 2.5 GHz base clock while the world was expecting 2.9 GHz.