The problems has been easily fixed by the developers
Valve has released a new stable version for its Steam for Linux client, but the developers have mistakenly launched a Beta version instead.Valve doesn't usually make mistakes, but the latest version of Steam released by the company has confused users.
“We had an issue with a beta update of the Steam Client escaping into the wild last night, you may have noticed an update last night and a new one this morning reverting that change.
“You can use the "File->Check For Steam Client Updates" to verify you have the most recent Steam build. If you wish to opt into Steam Client Beta updates then use the File->Settings dialog,” reads the official announcement.
Users don't have to do anything special in order to fix the problem, they just have to accept the new version when it's made available by Valve.
Download the Steam for Linux installer from Softpedia.