As part of its Open Strategy, Yahoo starting today is letting users add updates from their friends based on their activities on 20 other services across the Web.

These updates will appear in a FriendFeed-like fashion on Yahoo members’ profile pages and in Yahoo Mail. Already, Yahoo users can get updates from friends who use Yahoo services such as Buzz and Yahoo Music (but not yet Flickr, oddly enough). Now, they can add activity streams from Yelp, SmugMug, Picassa, StumbleUpon, YouTube, Pandora, Goodreads, SlideShare, and more (see complete list below).