Groups, a feature similar to Clans will be introduced in StarCraft II: Heart of the Swarm. It will be a more casual feature than Clans; Blizzard gives us a first look.
The Groups feature will be available for testing in Beta Patch 2.0.2 and will give players the freedom to associate casually and in large numbers. Like Clans, Groups will have designated chat channels, a News tab and an info tab, as well the usual description and Members roster. With Clans, players will only be allowed to join one Clan at a time and will have limited space for members. Groups however will allow players to join as many as 20, with almost an unlimited number of players that can join.
From what I can see these groups are very similar to Steam groups, which is awesome. Blizzard posted in the forum that they realize the similarity in features of Groups and Clans will cause players to use the two features interchangeably.
Currently, Clans and Groups are similar in functionality, so we anticipate that some people will use them interchangeably at first. Moving forward, our development focus on the Clans feature will be to add more competitive features, whereas Groups will remain geared around casual social interactions. We encourage you to keep these things in mind when creating a Group or Clan. How you choose to use these features will be completely up to you!
Bringing this social feature into Heart of the Swarm will make the game feel more accessible to new players; it will definitely contribute to making the game seem more social. Good to see Blizzard making an effort to expand the game beyond super competitive players, and make it easier for newcomers to feel at home.