Although we now have to trust the platform holders to declare their USA sales figures - given that NPD now does not - we should, of course simply believe them. We've got no choice. So...
In March in 2011: Microsoft sold 433,000 Xbox 360s. It's mentioned that it outsold Wii and PlayStation 3 with this 28% life in sales compared to March 2010.
Nintendo has announced that 290,000 Wiis were sold in the USA - compare that to the 557.5k units sold in March 2010.
Sony hasn't mentioned what the PS3, PS2 or PSP sold, it did however, point out that it saw "double digit growth across hardware and peripherals.” Whether that's percentage growth or just numbers it didn't say either... you've got to hope it's the former but until Sony pipes up...