1) Do you try to segregate your friends/contacts by service (e.g., business on LinkedIn, personal on Facebook)? If not, do you see issues with posting personal stuff (or business stuff) to your profile?

I've retreated from all such services - so I now keep business and personal handled by email, instant messenger and telephone.

2) Are more contacts always better? Some smart people I know seem to add just about anyone, including people they spoke to for a minute or two. Perhaps this is part of a personal branding strategy? When you have a big mass of undifferentiated "friends", does the overall utility of the social network decrease?

When I did use facebook, I found more than a few friends to slow things down. You saw messages which you didn't much care about and had to trudge through lots of friends names to find the one you want.

I hear what you are saying, VVV... I'm perplexed by what one blogger called the "loss of context" on Facebook, i.e., the formation of a big mass of "friends" ranging from college buddies to the most casual of business acquaintances (whom she may not even have met in person).

It seems that social networks have gone from friends being actual friends (in person friends, business associates, etc.) to random requests from people you met only briefly ("you stopped by our booth") to those whom you have never met ("like your blog!").

I'm not saying casual friends are necessarily a bad thing. Social networking theory places some value on being a "hub" or "connector", i.e., an individual with many diverse connections, and some of these casual friends may turn out to be interesting people. As you note, though, the logistics of having hundreds of friends may make a site more difficult to use.