Doug, you may know more, but read the fine print in the Press Release. Phase has become a "major shareholder", not the majority or controlling shareholder.
Without knowing the size of Phase's financial investment and the background to the investment, it's hard to evaluate the significance. For all we know, Mamiya was about to go the way of F&H and Phase is stepping in to keep it afloat. Since the parties have chosen to disclose so little, I would take all the conjecture with a major grain of salt.
The exact nature of the financials is indeed ambiguous: Mr Peterson explicitly mentions Phase One is now a "controlling shareholder," while the press release states "major shareholder" - there's a fundamental difference in the meanings and it would be good if Mr Peterson or someone from Phase One would clarify this.
In any case, it means that Phase One / Mamiya are now almost fully vertically integrated camera manufacturer, ie. they make the hardware and software for medium format cameras. I believe they don't make chips, which is the only part they still have to procure outside. This should create synergies and other buzz words which make executives giddy and M&A bankers rich - remains to be seen how consumers benefit.
Hopefully in the products; from the press release:
“And as a result of our close collaboration,” Mr. Midorikawa said, “new products are just around the corner. We plan to introduce both new leaf shutter lenses and even more super lightweight focal plane shutter lenses in 2009. We aim to offer the world’s widest range of medium format lenses for Mamiya and Phase One camera platforms.”