Standing in the crib help
How did you handle this? He doesn't know how to lay back down, so I've just been going in, laying him back down, soothing for a few seconds and leaving. He's waking a few times a night to stand up, and now we are reaching a crisis with his naps. He just stands almost as soon as I leave, and I think he's doing it because he knows I'll come back in when he does. I can't not go back in though, since he can't lay back down on his own.
Those who taught your babies how to lay down, how did you do it?
Tell me this is just a novelty/phase that will quit being so much fun for him in a few days! 
He's just finally falling asleep for his 12:00 nap right now, he stood and screamed for a good half an hour - I had to lay him down about 5 times.
I'm so bummed for him, because DH comes home at 12:30 to spend lunch with him, and now he'll miss him since it took him so long to fall asleep. Oh well, at least he is finally almost asleep!
Re: Standing in the crib help
I'd try not to do this... I feel like then you will have to get him used to settling down without you in the room.
We just let dd work this one out. I'd go in about every 5 minutes and lay her down. I wouldn't stay to comfort her b/c we didn't do that when she was fussing normally. I wouldn't really make eye contact or say anything... just go in and lay her down. It lasted a few days.