I’ve had a LinkedIn profile for a few years now. I first created my account at the request of a former co-worker who “invited” me to join. I found the information gathering process as invasive as the worst HR portal (Taleo comes to mind) and I didn’t like not having control over how that information was used. As a result I’ve left the majority of my profile incomplete, and if anyone is so interested they can come here and look at my resume. I’m also highly suspicious of the whole reputation concept, with it’s recommendations.
I have to think that in some ways facebook got their privacy features (and their business model) right, and that LinkedIn could have learned a thing or two.
Oh and another thing – I hate that they send me an unwanted “Network Update” email each week. The email claims in the fine print: “Don’t want to receive email notifications? Adjust your message setting.” Only there’s nothing in my message settings that allows me to stop said email.

I had a similar experience with Plaxo, which is why I eventually deleted my profile there… Every time I made the least change to my profile an email was sent to everyone of my contacts alerting them to the fact, unbeknownst to me.