The machines were spotted in a factory in China (not Foxconn) and their source wasn’t sure how far these were along. One could speculate that if they are in China they are being fitted for production. Their source said the company where they were spotted had a tight relationship with Apple. Quanta has been the rumored manufacturer of Apple touch screen tablet products for months.
At least one of these tablets was running OSX (10.5) Leopard.
Oh, and Gizmodo says this source has always been 100% reliable up until this point so it is likely a good tip.