Facebook at its developer conference announced that it saw at least a half-billion users access the site in a single day last week.

According to Inside Facebook, the most recent statistics from Facebook in June said that the company had more than 750 million monthly actives. However, in a spoof at the beginning of the conference, SNL actor Andy Samberg who was pretending to be Mark Zukerberg did show a chart suggesting the site has more than 800 million actives.

Facebook said 350 million of its 800 million monthly active users access the service through mobile devices.

Facebook has said many times that mobile is a big focus for the company. Mobile is of course the future of the whole technology industry.

In March 2011, Facebook rolled out a major upgrade to the mobile version of its site, and also noted that it passed the 250 million mobile user milestone. This means the company has gained 100 million mobile users in the past six months or so.