The news has a ring of truth to it, given that the two firms have manufactured the original PS3. The timing also makes sense, as Japan actually buys most of its game consoles during the summer vacation period (as opposed to the winter holidays in the west). Still, all of this info comes from anonymous sources, so take it with a very hearty helping of salt.
Assuming the news is true, it would mesh well with the PS3 Slim rumors we've heard so far, most notably that Ars Technica expected the units to hit the market in August or September. Add this to the string of rumors and leaks -- even some purported images of the unit itself -- and the PS3 Slim looks like it could be hitting the ground sooner rather than later.