We have a Parents Forum, which I think is the same sort of thing. Has been running for about a year.
It is entirely separate from the PTA, which deals with all the sorts of things that midnightexpress mentioned. The Parents Forum is specifically for parents to offer feedback about issues in school life and for the management team to consult parents about new initiatives/policy decisions.
For the first few meetings, it was a litany of complaints as everyone got their personal bugbears off their chests! But it has settled down into a pretty constructive forum. We have discussed issues such as homework policy, uniform issues, how we celebrate Christmas, how children are chosen (or not!) for sports teams and proposals for improving attendance (the only issue standing between the school and decent Ofsted grading!) The Head has used it to flag up new initiatives that are coming up and get parents' buy-in.
It has also been a useful way of getting some informed parents out into the playground. So when the classes were shuffled at the end of last year, the Head was able to explain her reasoning at the Parents Forum and those of us who were there were able to dispel some of the more ridiculous conspiracy theories that were floating around. We are also able to tip her off if playground gossip is raising some issues she needs to know about.
Tangible results have included a Parents' Maths Workshop, to help people understand how they teach maths these days. Also changes to the things we do at Christmas, to meet the desire of parents in KS2 for more of an "aaah" factor!
Attendance is not that high - probably 20 people max - but that does mean that it is possible to have a reasonable discussion, where everyone can have their say.