Yahoo and Facebook are to tie their services closer together.
The tie-up means people with a presence on both sites can have updates to one service mirrored to the other.
It also means that it will get easier for users of Yahoo's other services, such as Flickr, to share what they do with friends on Facebook.
Alongside the Facebook deal goes an overhaul of Yahoo's Profile service to make it easier for people to control what they share.
The deal means that people who maintain profiles on Yahoo and Facebook can link the two pages and cross-pollinate both with one update.
It will also mean that those who use Flickr, Yahoo Answers or the social site's video and music services can pipe any media or data they create to friends who use only Facebook.
The account linking deal deepens the relationship that Facebook and Yahoo struck in 2009. That made it easier for people to build a contacts book that spanned both services.
The refresh of Profile will see it re-named Yahoo Pulse. It will also get improved privacy controls so users can fine tune who gets to see their updates or view the media they put on the web.
The deal with Facebook also builds on a variety of other steps Yahoo has taken to help its users make more of social media.
For instance, Yahoo has struck a deal with social game giant Zynga which will see hugely popular titles such as Farmville and Mafia Wars work with its network. The games are due to be available in late 2010.