Valve’s Steam client has had a good beginning to 2012, with the concurrent user peak reaching above 5 million for the first time in Steam’s history. The record was broken on January 2nd 2012 with a total of 5,012,473 users using Steam at the same time.
The push of users could probably be linked to the recent Christmas Sale and Great Gift Pile Giveaway that Steam had going which ended on January 2nd, so it’s likely there was a lot of last minute shopping and achievement finding to grab the deals before the sale and promotion ended. The winners of the prizes, including the grand prize of every game on Steam, has yet to be publicly announced.
According to the other stats, Skyrim is still the most popular game on Steam and Team Fortress 2 is in 2nd place.