@ Carl some more
For example, one of the key games at Sony's E3 2009 press conference was Uncharted 2: Among Thieves, yet the original game itself isn't close to breaking the 750,000 unit mark in the United States. According to Jack Tretton, CEO of SCEA, Uncharted has sold more than 2.6 million copies worldwide, however many of those are copies bundled with PS3 systems (which are not counted here), not software directly off store shelves.
One could also look at Resistance 2 which has sold less than 750,000 units in six months on the market, to a userbase of 6 to 7 million owners. For a game promoted as the latest and best on the platform, opening month sales of 385,000 units seems exceptionally weak.
We could, for example, compare to Gears of War on the Xbox 360. The original Gears of War, exclusive to the Xbox 360, racked up a cool million units in its first month on a userbase of only 2.9 million users. By the end of the second month, December 2006, sales were over 1.8 million units.
The sequel, Gears of War 2, launched with sales of 1.56 million units in its first month to an audience of 12.4 million users. By the end of its second month, December 2008, it hit the 2.3 million mark. For both Gears of War and its sequel, sales were far stronger than Sony managed with Resistance and its sequel, even when taking the relative sizes of the userbases into account.
We could also look at a multiplatform action game sequel on the PS3 like Call of Duty: World at War, which just happens to have launched around the same time as Resistance 2. World at War sold over 1.1 million units during the last two months of 2008 while Sony's shooter moved just over 500,000 units.