Many women go several hours, days or even weeks after ROM before labor sets in. She needs to rest, stay hydrated, take big doses of vitamin C and keep absolutely *everything* out of her vagina (no cervical checks!). In many cases, this is a sign of even slight malpositioning (ROA instead of LOA, for example), so working on spinning babies techniques or seeing a chiropractor or acupuncturist for help with fetal positioning could help get things going.
This happened to me with my first and I ended up on pitocin. I didn't know any better then, but now I know that one should just wait and work to get baby in the right spot to put that pressure on the cervix. Best of luck to your friend--hope she's holding her baby by now!