If we use a desktop/mobile client which simultaneously publishes to Twitter and Facebook, our @ reference to twitter user names do not hold any context in Facebook. For example, if I am using @sandeep in a tweet, it holds no context on Facebook message although I have the same friend Sandeep on facebook. We need to map users across networks so that user A on Network X can be mapped to user B on Network Y.

Social networks themselves can't be expected to maintain these identities. So, it is up to Activity Streams to contain these mappings. That is how we can completely take the social graph across different websites.

We need to develop a method to perform this operation.