Email remains the primary communication medium for inter-organization communication. Federating instant messaging tools (i.e. allowing staff in partner organizations to conduct IM sessions) is another excellent way for staff in different organizations to collaborate across organizational boundaries.
... For sure, there is a generational element at play here and as the "email generation" move out and the digital natives move in, social tools may well assume ascendancy in the corporation.
Activity streams are not always the best choice for communications and collaboration, but they are nevertheless compelling tools for sharing with our colleagues.
A challenge for all knowledge workers as we go forward is that we don't simply move our email inbox problem into one or more activity streams — same amount of clutter, but with more places we now have to check. Where the number of persons and groups being followed is large, the potential volume of information in the stream is massive, leading to a new form of information overload — let's call it "activity update overload." Improvements in search and filtering tools by the social tool vendors have made the task of finding information in an activity stream easier, though there is still room for improvement here.
In closing, activity streams are a new capability and as a relatively immature enterprise tool, organizations are still working out how best to use them. Perhaps the key benefit of activity streams will be not that they replace email, but that they help us to finally get control of our email inboxes, by removing the large proportion of useful, but non-time critical communications (to the activity streams) and leaving us with just the emails that we need to work on today.
Great analysis posting on the value of Activity Streams and the rising importance of Social Filtering and Analytcis. I will give my perspective this week, as soon as my German language posting on Activity Streams is being translated into English ;-).