I don't know, I get a lot of inquiries through LinkedIn for writing, but most don't actually seem serious about doing business, just curious. I'll probably upgrade once I actually see some return on the time I've invested in the site, but until then they won't get a dime.
I'm in the same place as you. Made a lot of contacts on Link'dIn and Plaxo. Got a few inquiries, but nothing solid. In talking to a lot of business people( I do Commercial P&C), they all say the same thing....and many have backed off from using it.
I do have a friend who is a fund raiser for a mega non profit that has had some success with it, though.
To me, it's like that funny shaped knife that comes with a cuttlery set....it's probably great for something, but no one knows how to use it.