LinkedIn, some assembly required

I've generally viewed LinkedIn as a giant online phone book, with the added benefit of allowing me to keep up to date on career changes of folks I might not normally speak with. Thom Singer has a rant up today on his experience with LinkedIn. A user took offense to him refusing to connect, after he received the generic "You're a person I trust; let's link up" LinkedIn email.
Thom has a policy of "no linking unless we've shared a meal or a beer"...the question for him really is, is that the social norm at this point on LinkedIn> Given he's a public speaker, there are going to be a number of people who feel as though they have a connection, and would like to link to him... It's a tough call, since LinkedIn can rapidly turn into a network of people who want to make connections to sell something. Generally, people DO write nice intros, but I often find myself replying that I'll forward something, but it's going through someone I dimly know, and I can't verify it'll get to the end recipient. I've often thought that LinkedIn should allow some granularity with new contacts, for advanced users..something that would allow us to limit the contacts that requests might be forwarded on to.. Eg, if I've linked to person X, because we met at a trade show; maybe I don't want to forward requests through him, because I don't feel there's a connection there.
Thom's got to do what's right for him, weighing whether the occasional antagonized emailer is worth a clean network. I suspect for him it is.