MK - my dd has never been a good sleeper, BUT she has been standing in her crib for the last 3 weeks or so. All I can advise is be consistent like Kate says.
I go in only when it's a "real" cry. Then I put her down in a way that she would get down herself, and I will stay if she is settling, but if she goes to get up again I say night night, and walk out (almost so she knows it's time to sleep and I will now fight her, but I will not reward her by staying in there...if she says down I say until she is drifting to sleep - and I must say she is letting me leave sooner and sooner these days). If she "really" cries, I go right back in a do it all again. It she is just mad, I will wait a minute or two, but I usually know it will turn into a realy cry so I really listen. Now after 3 weeks, she doesn't get us as much and she settles in a fraction of the time, homefully we will be through this phase soon!
Good luck. This too will pass.
Also, note to all of you things seemed to get better with a longer awake time (3 hours) and no catnap.