Laugh Track

I can absolutely confirm that it is recorded in front of a live studio audience. I was in the audience for this season's episode, "My Name is Rob." The laughter is genuine. It may be augmented in post-production but it's definitely real. There was a warm-up comic working the audience to keep the energy level up before the show started and during the times when things on set were being reset. He made general suggestions about laughing as boisterously as possible overall but there was never a sign or anything that said, "Laugh now," or anything like that.

As I recall, they showed at least one pre-recorded scene at the appropriate time because one of the actors was not going to be available for the studio taping time (Jay Leno apparently had a stand-up gig that conflicted with the taping). I suspect they do the same thing (although I have no direct knowledge of this) for scenes that are outdoors (e.g. Mutton Busting) or may be otherwise too technically difficult to film on set. While I'm sure this is done for the sake of adding the audience's laughter to the audio track, it's also to the studio audience's benefit to be able to watch the scene at the right point to get the flow of the entire episode.

I do have to wonder because earlier in the season Tim directed an episode, and they had at least a partial audience.

You most likely won't read it but I'll reply anyway:
It actually IS a laugh track!
Yes, it is recorded in front of a live studio audience but the laughter is recorded separately into its OWN audio track. They have microphones above the audiences heads and those are recorded by themselves (maybe even separate from each other so there would be several tacks).
You can NOT hear the audience through the microphones (mostly so-called boom-mics) that record the actors since they're made to JUST record the actors. Mostly the mics are above the actors (and you can sometimes even see them - watch Two guys, a girl and a pizza place - you can see the mics ALL the time!).
After the taping those several recordings are put each into a track of an audio mixer (in the computer nowadays) so they are separate tracks with the actors and separate tracks with the audience's laughter - ergo laugh tracks.
Most people though think laugh tracks are pre-recorded laughs added later which was only true for parts of "How I met your mother" and "Anger management" which were not shot in front of an audience. They were taped and THEN shown to an invited audience after they were edited.
"How I met your mother" however had often scenes never shown to the invited audience due to the secrecy of those scenes and used canned laughter for the.
I have been to tapings of several shows and behind-the-scenes of "Big Bang Theory", "Two broke girls" and "Two and a half men" (but with Ashton Kutcher). I was able to see and talk to cast and crew on all three shows.
Oh - and by the way: The main reason why the laughter is so often and loud... You have to imagine that the people who go to the shows are BIIIIG FANS of these shows. They love the shows so the laugh more. No need to tell them when to laugh. But yes, there's always a comedian to keep the people entertained while the wait for set and actor changes - so called moving-on. The audience gets water and food - mostly pizza or sandwiches - and candy. It's fun!