I'd say most projects can be knocked together to a basic proof of concept in a day. However getting it to be able to support 100 million users (as per the article), or even be worth showing takes a lot longer then that.
Keep in mind that is the outer bounds. I am sure no one would complain If a team delivered a quality product in some fraction of that six months time period. Even more, though six months sounds like an eternity to a startup with 7 months of "financial runway", for teams used to the bureaucratic pace of yahoo, 6 months is likely considered to be breakneck.
The first "version" could be the wrong term. I'd be asking how long did it take for the first "user facing version" to be produced. I imagine 6 months isnt far off, maybe less but it would be a very restricted beta.
