Let me preface this by saying that Lily's mattress is currently tilted upwards (so her head is above her feet). In addition, we still have a drop down crib. When the side is down, Lily can easily grab the top of it.
With all that said, we've been working for 4 months, trying to get Lily to sit up in her crib by pulling on the crib rail. Well, today, she did it! I am so elated - I can finally start worrying about Lily getting into trouble in her crib!