ad. 1 - we have a use case of group of companies (4 different companies 1500 people in total). That is why we will have this external user invitation feature. I think that this could be used for partners and customers in cases like customer knowledge base (support knowledge base).
ad. 2 - Chatter/yammer has problem with the activity stream (we've discovered this while working on Discourse and the next version will get rid of that problem). Activity stream just like in Facebook is ok when you read content you don't care about (like your network updates about what that had for breakfast etc.). If you have customer communication or any other important business communication there is no way that you'll not be frustrated with facebook-like interface after few days.
ad. 3 - Good point - we are thinking of the value prop for the HR dept. I think that karma could be a great tool for HR for people development rather then promotion decisions :)
ad. 2 - Chatter/yammer has problem with the activity stream (we've discovered this while working on Discourse and the next version will get rid of that problem). Activity stream just like in Facebook is ok when you read content you don't care about (like your network updates about what that had for breakfast etc.). If you have customer communication or any other important business communication there is no way that you'll not be frustrated with facebook-like interface after few days.
ad. 3 - Good point - we are thinking of the value prop for the HR dept. I think that karma could be a great tool for HR for people development rather then promotion decisions :)