Got to love the WSJ.
Pick any non-consumer-facing industry where the average person doesn't know the players, and everybody is "little known". That doesn't really tell you anything about their actual businesses or reputations.
Something like "Social coding startup GitHub, hugely popular in the coding world, ...." would be a whole lot clearer.
Little-known, though technically correct, implies that they are not well known in any circle.
WSJ is supposed to provide good reporting with strong bias towards informing potential investors (as a financial/business news paper). The wording choice doesn't make a strong case for value associated with the company and sounds like some no-name co. just got a pile of money that they are like to lose. (An exaggeration on my part for illustration purposes only.)
Wasn't that temporary during the kernel.org debacle?