Foursquare? For real?

Like what's gonna happen if they have a couple of corrupt data? A minor incovenience at worst?

Is anyone gonna lose millions? Nah. Anyone gonna die? Nah. Anyone gonna get sued? Naaaaaah

Also Facebook uses MySQL for their primary data. Pretty sure it's the same for ebay. Don't know about Adobe, I bet it's the same deal there too.

People get so excited when they hear some big company using X, but they have no clue in what capacity it's used. I can guarantee you that all the data that matters, that need to be consistent and whole are in some kind RDBMS.