Em I had a scare a few weeks ago, I woke up with a puffy face and really puffy feet. I called my midwife to ask her advice and she quizzed me about any other symptoms (headaches, spots in front of the eyes, etc) I said no so she said if I was concerned to go to my GP and ask them to take my blood pressure. I did and though it was up on what is normal fir me (I have naturally very low BP) it was definitely not high.
Pre-eclampsia is a risk, and sounds like that might be what your friend had, but as comms says, if you are being seen regularly by your midwife and having your BP and urine checked then it is probably just standard pregnancy fluid retention.
I find the best thing to help with my puffy feet is to:
a) avoid sitting for too long a period - get up and move around even if it's a few minutes once an hour;
b) prop your feet up whenever you can - I've taken to putting cushions on my coffee table so I can prop them up when I'm on the sofa;
c) try sleeping with your feet on a cushion, or, even better, see if your DH will stick some heavy duty books under the foot of your bed so that your feet are raised a bit at night;
d) before you go to bed spend a few minutes circling your ankles and flexing your feet to help move the fluid around.
Don't stress like I did, puffiness is pretty common in late pregnancy, but talk to your midwife if you are ever worried.