These articles all reference the FCC regulatory filings which merely list a VM model number (and a bunch of other model numbers) and say nothing else. That doesn't mean that VM will or will not get the Optimus Black - it just means that LG is authorized by the FCC so sell a phone in the U.S. under model number VMxxx. Sites like phone-arena.com troll the FCC site for interesting filings, make guesses and assumptions based on incomplete info., publish those guesses and the information gets twisted every time it's re-published by sites like geeky-gadgets until the headline reads "Republicans refuse to buy Obama a Sprint iPhone 5 for his birthday!"
I think (also hope) that VM will get the OB eventually, but let's not get ahead of ourselves. The fact that a model number appears in some government paperwork doesn't really tell us much.
As far as the Sprint release date goes, there's a leaked product plan document floating around (from Best Buy I think) that shows an -October- 2nd official on sale date for the Sprint version. In the past there has been a four month gap between FCC filings and Sprint official product debut dates, which also puts us into October. (There was also a four month gap between the Optimus S and the Optimus V going on sale which would put the VM OB into February 2012 if that pattern holds up.)