Uber is an e-hailing company based in SF. They originally started out only offering high-end cars that people could summon with a mobile app, but now they also include cheaper cars in their lineup (the cheaper service is called UberX).
Their HQ is in the Mid-Market area at 1455 Market, in the same building as Square and next door to Twitter. In 2013 they signed a 10 year lease on 88k sq ft (the entire fourth floor) of the building. They remodeled it at a cost of $12mn (Uber spent more than any other SF tech company on remodeling and renovations in 2013) [source]. This is what it's like now.
The CEO of Uber is Travis Kalanick.
Uber and Google
"Uber is first third-party app to ever to be integrated into Google Maps. Last summer Google Ventures, the corporation's "entirely" separate venture firm, was part of a $258 million investment round in the e-hailing company." [Valleywag]