via next gen

Anecdotal evidence from US brick-and-mortar retail outlets suggests that the 20GB version of the PlayStation 3 is heading for extinction, but Sony tells Next-Gen that's not the case--at least for the time being.

"The type of model found in stores is completely up to what the retailer orders, so if they don't see a big demand for a particular SKU, they simply don't order it from us," explained Sony Computer Entertainment America PR head David Karraker. "We continue to manufacture both."
"At this time there are no plans to change our US model offerings," Karraker stated.