This week in Social Media: LinkedIn gets hacked/Foursquare gets a makeover

A Russian hacker has stolen 6,458,020 encrypted LinkedIn passwords and posted them online (without usernames). The breach comes on the heels of news that LinkedIn’s iOS app potentially violates user privacy by sending detailed calendar entries to its servers. In simple terms, this means an attacker might be able to crack many of the passwords using very cheap resources in a relatively short amount of time.

If you’re a LinkedIn user, make sure you change your password right now. Furthermore, if you used that password on any other online service, we recommend you change those passwords as well.

Follow @LinkedIn and @LinkedInNews for more information.

In other news, Foursquare finally launched its redesigned app. The main difference between the new and old app is a (much prettier) packaging.

The new look is pretty clearly aimed at letting people interact more with others on the site — those that they know already, and people with whom they may not be acquainted yet. Each profile page features the user’s photo, location, short bio, and various contact information and social media profiles front-and-center. The home page’s new layout also makes it more inviting to click around to look at the latest activity by your friends. This seems pretty clearly built to make Foursquare’s experience “more sticky,” and encourage users to click around on it more often and for longer periods of time.

Photos now take center stage in both the Explore and Friends tabs, making them look more like Instagram feed than a list. User profiles have a tiled interface that allows users to access stats, lists, badges and tips from one screen instead of scrolling.

Foursquare also finally added “Like” function. Users can now click a heart button on venues, tips, lists and friends’ check-ins.