The social functionality in SharePoint 2010 has been massively improved from the previous versions of SharePoint, and one of the areas is around the concept of Social Feedback.
Question: How many times have you found a useful link somewhere on the internet, but had no way to usefull record that and get feedback from your colleagues?
Well, SharePoint 2010 social feedback can help with this, you can now "tag" any source on the internet (or intranet) which has a URL. This is stored in your "tags" section on your My Site, and also appears in your "Activity Feed" (which is one of the new areas in the SharePoint 2010 My Site).
Other users can also post "notes" relating to your tag, which effectively creates a discussion board around the "tagging" activity, allowing conversations around something that has been tagged.
Now, one of the key points is Security Trimming. Lets take this example: what happens if you Tag a document that someone else doesn't have access to?
The good news is that social tagging uses the Search Index to provide security trimming on content that is stored in SharePoint.
This provides the capability for senior managers to tag confidential documents (and hold conversations about that using notes) but those tags (and notes) are not visible to anyone who doesn't have read-access to the document!
On top of this is included a Ratings feature, where you can rate content within SharePoint lists (finally, the death of third party "rate my content" web parts).
This means that SharePoint 2010 now has similar social feedback functionality as other products like Digg or Delicious, in that you can tag and rate content, and other people can interact with that "tag" creating a discussion.
All of the Social Feedback information in SharePoint 2010 is stored in a separate "Social Database". This sits alongside the Profile Database.
There are then "Gatherers" (Timer Jobs) which will collect all of the changes to both the Social Database and the Profile Database and this is stored in another database for Activity Feeds (the Activity Feed Database) with foreign key pointers back to the Profile Database (so you know who's activity it is).
The performance is impressive, aiming for 2000 requests per second, and in terms of storage they are looking to support over 600,000,000 rows of data! They claim that this is sufficient for activity (including social feedback) for 400,000 users over 5 years!
You can also hook into this process yourself. You can build your own "Gatherer" jobs to collect information from any data source that you like.
A good example is a CRM database, so that you can show activity in CRM in the My Site Activity Feed, showing when people schedule meetings or achieve sales activites.
All in all the Social Feedback and Activity in SharePoint 2010 is shaping up very nicely. The performance is something that they are still working on, so don't expect amazing results in the Beta version, but Microsoft are already using this for all of their employees so the dogfooding will make sure that this is given all the attention that it needs!