it is here... Pentax 645D

"...dust-proof, weather-resistant construction with 70 special seals, outstanding cold-resistant performance to assure solid operation at a temperature as low as –10°C, and a newly designed shutter unit with a top shutter speed of 1/4000 second that can withstand as many as 50,000 shutter releases..."

Fantastic. Half the price of the 40MP medium format Mamiya and only slightly higher than Nikon D3X. I've been waiting for a 24MP D700X for scenics but will now seriously consider the Pentax. I used to use an RB67, medium format is magical. I can't wait to see some images from the Pentax. It could potentially put a dent in high end Nikon and Canon sales.

I think it very well may put a dent into the high end Nikon/Canon DSLRs. Suggested retail is $9400, so presumably the street price will be under that and in the territory of Nikon/Canon.
I can't wait for it to hit the US market!

Thanks Yuri - i have been impatiently waiting this. What is this about initially only being available in Japan - why would Pentax do this? The specs in the dpreview article say "Usable lenses: Pentax 645AF2, 645AF, and 645A mount lenses" - are there any other sorts of Pentax 645 lenses? I have some manual focus lenses marked Pentax-A 645 - am I correctly assuming these are 645A mount lenses?

Peter, I think you are right Pentax-A = 645A mount lenses. This is for all the Pentax 645 lenses then, A, FA and now D-FA. Wonderful news. I did not catch the A series lenses.

What about the Leaf Shutter 75mm lens - marked as Pentax SMC 645 L.S. 75mm f2.8? Will it be compatible?

Compatible, yes-- but whether it's a good fit, we'll have to wait and see. Consider that because it's MF, the pixel density of this sensor might outresolve your lens. If you've got a one capable of only 60 or 70 lp/mm and a sensor that's capable of close to 90 lp/mm, what's the point of having that 20% better resolution than a 24MP FF DSLR (that is, why spend nearly $10 grand on a body when $2K would easily net you the same or even better results)?
I'm glad the 645D finally has seen the light of day, but for now it seems like the best bargain of all is to have Ektar 100 loaded in my P645N easily outresolve my old 35mm SMC-A lens.

Thanks Ivan - so a Pentax SMC 645 lens has the same (or compatible mount) as a Pentax-A SMC 645 lens?
Not sure what you mean by this:

it seems like the best bargain of all is to have Ektar 100 loaded in my P645N easily outresolve my old 35mm SMC-A lens

I've resisted selling my 645n system and lenses on eBay, hoping for this day. The 645D may well affect marketing and product strategies at Canon and Nikon, bigtime. I suspect the initial release is Japan only to avoid any stumbles in the US market (hardware/software bugs) and probably not a bad idea. My 645n has been dead reliable and is almost twelve years old. I hope the 645D is the same way. I've been using many of my 645 lenses on my Canon 5d mkII with an adapter and most of them outperform equivalent Canon L lenses. The 5dmkII will become my backup at some point in the future.