They said they have VC funding. They did not mention which VC firm (or individual) invested in them. They did not mention how much was invested in them.
There were no filings to add people to their board (which is what happens when someone puts a chunk of money into a company).
You should examine other press releases by firms who have gotten venture backing. If it is good news, they always announce the name of the firm or individual and the amount that was invested. Moreover, the firm also announces the investment and places the company in their portfolio page. If the amount was paltry (like $100,000) then they probably just want to say "backed by VC" and let people presume that they have funding.
"Always"? You speak in a lot of absolutes... Ever heard of silent partners/investors? Not everybody who invests in a venture wants their name on the building, or in the newspapers.
VC firms don't generally do silent partner investments. We were talking about Venture Capital funds, not an angel round or rich uncle taking a stake etc.
There is no "stealth mode" consideration here since BFL has been broadcasting their intent and methods.
"Generally"... A minute ago it was "Always" now it's only "generally".