Update: Thursday, her water broke... or started to leak anyway. They went to the hospital. Her blood pressure was high so they took care of that. She was dilated 1 cm. They decided to keep her in the hospital.
In the afternoon/evening she started having contractions and got to 3 cm and they tried to slow them down; as long as baby and mama are not in distress, it's better to let the baby develop as long as possible in utero. They're giving her steroids (to accelerate baby's lung development), antibiotics (for both mom and baby) and a lot of IV fluids (to allow her to replace the amniotic fluid that's been lost).
They're closely monitoring blood pressure looking for any signs of infection. My son texted this evening that the contractions were picking up again this evening, but later texted that they were Braxton Hicks (false) contractions. They estimate the baby is already over 5 pounds, so that's a positive. The doctor said if they can get even a few more days before baby is born, it would greatly improve the baby's health at birth.
So yeah. Wait. And hope and pray for the best.