My DH and I have once, at about 5 weeks postpartum. I had a c/s, so you'd think things would be no different, but no... it really hurt, so we haven't tried again yet.
The girls in my BB group have talked about this a bit, and it was suggested that the hormones involved with b/f might make things a bit dry 'down there', which is why it probably hurt for me.

I hope it gets better.