Does Connecting on Social Networking Sites Help Professionally?

Recently I started a discussion on Linked in to gauge whether connecting on Social networking sites like Linked in or Facebook or Twitter etc did really help them professionally. I got a lot of response from people. I'm going to put all their comments here and then we shall salute such sites for making serious work possible and lifting networking from the realm of meaningless dating sites.
Me: The link between jobs and connections on Linked in. A fellow networker Monique Fritz found a job on Linked in. Has anybody else found a job on Linked in? How does Linked in or networking help in getting jobs and is there anybody who has got more business through contacts or through networking groups?
Roger Toennis: My two prior jobs one employment and one contract were found through Linked in.
Mathew Keanne : I have had several good leads come from jobs on Linked in which is good, for my personal search I use the jobs here and on several other sites/ services. Try indeed.com for an aggregated search service across all the main job sites.
Jackie Ernette Z Athey: I received a small contract through Linked in. I had lost touch with a previous client and found him through Linked in. By Serendipity, right after I contacted him, I received the OK for the contract and contacted me.
Well lucky for you Jackie and she has tips for us too.
Jackie Ernette Z Athey: You still have to be active though and not think that because you are connected to x number of people you can just sit back and wait. This is true of any networking group.

The next comment by Allison Simmons will definitely tell you that all is not hunky dory as far as networking sites are concerned and you have to be circumspect like with all things in life.
Allison Simmons: So far I have not received any leads through Linked in, although I have received some good feedback on my resume as well as some good ideas. I remain optimistic, but have also found that there are a LOT of network marketers here (and I wish them all the best of luck and good fortune as well as a LOT of links to jobsites and fictitious jobs that are posted by affiliate marketers. Unfortunately, this group has found the unemployed a great target and are sending us by the droves to their websites and even jobs that are not legit........
The nest one is a self employed professional just like me, lets see what she has to say,
Marianne Weidleinn: I'm self employed and live in a small rural community that cannot even support my minimal income needs. Therefore I need Linked in...........
I have been active on Linked in for two months and I have two new clients and some are interested. I have connected with many old friends..........
You need to be clear about your intention with Linked in, determine specific goals and how to use Linked in features to further those goals............
Rick Peterson: I have found several partners for our project To Bring Back the American Dream http://www.bringbacktheamericandream.com/

I had several other inputs but most did find networking helpful and I think this should drive home the fact that when you set out your mind to do something and have a clear plan of action you find several helping hands along the way. More on my musings later please keep those comments coming...