Pentax has announced a rebate on the 40-megapixel Pentax 645D:
Photographers who purchase a 645D camera body between March 11, 2013 and March 31, 2013 will receive a free D-FA 55mm lens.
They will also be eligible to receive a $500 PENTAX VISA® PREPAID CARD on the purchase of the Pentax 645 25mm D-FA lens and HD 90mm lens when purchased at the same time as the body, for a total savings of up to $1,000.
My review of the 40-megapixel Pentax 645D dates back to Dec 2010 - Feb 2011. The sensor is quite nice, but even here in 2012 the system remains underserved by top-performing lenses, though the 25mm and 90mm lenses predate my review, and might in fact offer high-grade performance. As I wrote back then:
The 39.5 megapixel 7264 x 5440 Pentax 645D breaks new ground in both price and functionality for the medium format market.
The Pentax 645D uses a 40 megapixel Kodak KAF-40000 full-frame CCD sensor producing 7264 x 5440 pixel images on a chip that is 44 X 33mm, with 6 micron pixels — a pixel size almost identical to the Nikon D3x and Leica S2. The sensor is 68% larger than a Nikon D3x, and 7% larger than a Leica S2.
The 645D does not use an anti-aliasing (blur) filter, so the actual per-pixel detail is improved over conventional DSLRs, especially on low contrast details.