One feature that has received a major upgrade in 2013 is the activity feed and microblogging infrastructure. The primitive functionality in 2010 has been replaced with functionality that you would expect of a social computing platform.
In SharePoint 2013, this infrastructure is built on the traditional lists, a lot of JavaScript and some server side API’s. The major change from 2010 is that all the content is stored in the user’s personal site, not in a common database. This means that all users have to provision a personal site, something that could have a great impact on your data storage strategy. If you have 10 000 employees using this, you will have 10 000 site collections to keep track of.
The information being published in the activity feed is determined by privacy policies and what you have chosen to expose. The first time you access your My Site, you are asked yo updated the privacy settings.

To start things off, here is a picture of the updated activity feed.

It’s possible to reply and like status updates. It’s also possible to select different views to show different types of activities. i.e mentions.
Using the @notation, it’s possible to mention other people. SharePoint will then provide automatic completion. The # tag syntax is also supported where it will use values from the Taxonomy service.

Another aspect of the activity feed is the site feeds that may exist on sites that you follow. This could be various community sites. The site feed has to be explicitly activated since it’s not on by default.

Once this has been activated, you can cross post into any community you are following.

With this functionality, SharePoint is eating into the territory previously held by companies such as Newsgator. It will be interesting to see how they respond.