Ok, I found the latest reference to it in this forum
http://forums.rennlist.com/rennforums/showthread.php?t=214596&referrerid=27688
It references a January, 2005 article in the German magazine "Auto Motor und Sport".
http://www.auto-motor-und-sport.de/d/77599 and
http://auto-motor-sport.de/d/77671
It has the range listed as 100K-150K Euros (~125K-175K Dollars at the time) and has some good pics of a red Panamera.
Here's a link to a MotorWeek article from3/15/05
http://www.autoweek.com/news.cms?newsId=101990 with good pics of a silver Panamera.
This has been discussed in the 928 forums for a while as possibly being the "new 928". Since 928 production was stopped in 1995, owners are longing for a comparable replacement. The Panamera, with a water-cooled V8, hatch back and 480+ HP is the closest thing to date. Also, the original 928 was revealed in the early 1970's as the "Panamera concept car". The price range of $125K+ would be in range with the original 928. Mine was $65K in 1987, about $120K in today's dollars.
I know as a Boxster owner it's hard to understand, but to a 928 owner there just is no better automobile so the hope of a new model is huge. I can't explain it. Even last weekend when we were flying through the mountains, while it was a blast in the Boxster, I just kept thinking "I wish I had the 928 today". The gearing has a much wider range and being thrown back in the seat when you hit the gas is a nice feeling.
Here's a comparison of the Panamera to a 1985 928S: