GameDaily BIZ has heard from a corporate retail source - not from Best Buy, but at another major retailer - that something is definitely "afoot" but he "can't really comment (until the 80GBs are gone.)" [parentheses statement added by source, not us - Ed].
Moreover, we spoke with Janco Partners analyst Mike Hickey who told us, "Sony is likely dumping the 80GB version because it has failed to meet internal sales projections."
UPDATE2: Well, this is interesting. We just heard from The NPD Group who told us, "In the last quarter (when both were on the market), the 80GB sold more units than the 40GB." When pressed for a more exact breakdown of the sales data between the two SKUs, NPD said they could not provide that. It's certainly a surprise to us, however, that the more expensive 80GB would have sold more than 40GB, which many have attributed the PS3 sales spike to.