Yes and yes.
Linkedin is a great resource. I don't even use a resume anymore- just link to my profile. Most of my work is word of mouth but even so when people see all the people we have in common it makes things easier. I've had people comment on it.
I don't think I've gotten any work directly from LinkedIn, but that's not why I use it. I have reconnected with many colleagues whose names I wouldn't have remembered if they didn't pop up.
Also, by seeing when colleagues have changed jobs I can tell where the work is- when there's a new show or crewer in town. I have gotten work that way because people assume I'm too busy, when that might not always be the case- especially for the right project with the right people.
I can also tell when a company or show is headed south because of the increased LinkedIn activity from their employees.
Anyway, I'm a big fan and have used downtime at work to play around and see how it works for me.
Forgot to mention- there are some companies/individuals that post worthwhile openings on LinkedIn. Nothing has worked out for me yet, but I have 'shared' those updates and hooked some friends up, which pays off eventually. Most of the larger companies I follow don't post anything meaningful.