There is a number of attempts of Social Profile Aggregators out there like ClaimID or ProfileFly or Wink (to name the best of those) but they all do not solve two major problems of Social Network Integration.

Essentially the first problem is how to maintain referential integrity of you numerous social network accounts. For example you have a network of friends at MyBlogLog and on a dozen of other communities as well. Now on each community you have to recreate your network by adding friends manually and the worst of all you have to rely on their usernames which may happen to be completely misleading (imagine someone having different usernames in different communities.

Secondly the problem is how to automate crossposting of your important messages to different communities at once. There are attempts to do it with feeds but the real solution will be to use XML-RPC.

When these two problems are solved you may declare a working Web2.0 social networks integration.

PS I know this 'cause I am currently working on such project ;-)