The Google Reader team just announced the addition of an important new feature to Google’s popular feed reader: you can now comment on any item that your friends have shared with you. In order to keep track of these conversations, Google has now also introduced a ‘comments view’ that will only show an excerpt of the post, but which highlights the comments your friends have made.

Whenever a post in your list of shared items has comments, a little speech bubble will appear on top of your friend’s icon. If more than one of your friends has shared the same item, Google will present you with separate conversations under each person who shared it.

The comment feature is also available in the mobile version of Google Reader.

As of now, the comments you make in Google Reader remain in Google’s silo and won’t be syndicated back to the original blog. It is not clear if Google will give developers access to these comments so that they can create plugins that aggregate these Google Reader comments and display them on the original post or on an aggregation service like FriendFeed. In the announcement, however, the Google Reader team stresses that it wants to give its users the ability to have private conversations.

Google has been relatively slow to add social features to Google Reader and most of the discussions around shared items now happen on other services like FriendFeed and Facebook. It will be interesting to see if users will actually use this new feature in large numbers, but it is definitely an interesting addition to Google Reader. In the announcement, Google specifically mentions that it has “much more planned for this feature,” and we can’t help but wonder if Google is planning to allow users to comment on any item in Google Reader (similar to the SearchWiki functionality in its search engine).