So many social networks out there... It's hard to ...

I doubt it.  Too many people like isolating themselves into little groups...big groups scare them plus the bigger the group the more chance of arguments and disaccord. 

 I think the social groups will stay diversified not only based on topic but inside the topics.  For instance I'm in several John Denver fan/social groups.  There are some members in one that would never dream of joining another group because of a topic that might be brought up that they do not agree with but in the group they are currently in it would never come up.  Some groups are simply more open to discussions than other therefore keeping the diversity going.

Not even in beta yet, Google's sponsored SocialStream is aimed at interconneting existing social networks.  Socialstream would let you post content, such as photos, blogs, video, comments etc. to and from any participating network.  Sponsored does not mean it is a done deal and Google will launch it but it is in the works. 

There are also a bunch of other sites working on aggregating your social profiles.  Read more here: http://mashable.com/2007/07/17/social-network-aggregators/

How long will you have patience to meet new people, form new relationships and find new interests in the offline world?

And why do you keep all these obscure wrenches in your garage when you could use a hammer for everything? 

Yes, moving between social networks is a pain, and a lot of us are feeling the social networks fatigue. But upcoming standards like OpenID, FOAF & XFN, and established ones like RSS, are easing the pain of moving between different social networks. And there is a lot of grassroots thinking about which other standards are needed to let you move with ease between serviced. 

You don't have to keep track with all of them though. As you move to a new social network, leave some of the old ones behind you :) Natural selection is working here too. 

But, no matter what network I am on, I promise to always add you as a contact :) 

Convergence is already happening in facebook - the whole idea is using one identity with many networks (like yedda).

example: 
http://booksoncampus.com for example relies on your facebook identity to log you in

I have just joined facebook and I'm frustrated at the fact that I have access to people in my network but all the content is on my blog not on my facebook profile.

Maybe convergence doesnt need to happen but content needs to be able to be shared between different networks much better than it is now.

A good article on exactly this question and its relevance to FB is posted on

http://wisdump.com/web/the-ebb-and-flow-of-social-networking/

It's not my article, before you ask, but it does point out that the usual social networking site goes through the usual product life cycle (the S curve). FB and MySpace both have critical mass and are managing to extend the cycle peak by adding new functionalities, e.g. music, pics, etc and eventually I am sure that they will incorporate office tools as well to blend the whole of the user interface.

One suggestion I could make is that the next app to be developed should be a "Chinese wall" between your friends list. According to a recent Viacom study, over 40% of network users are over 35 and several older colleagues have told me that they are having problems when they want to connect to their teenage kids due to the "street cred" appeal. If friends could be separated, do you think that there would be a need for distinct network sites?

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 ;-)