Our current system (using the email sent to the
support ninjas as "real" feedback) has the disadvantage of being opaque, but otherwise serves our needs well. We've discussed making customer requests more public, but we haven't found a method of doing so that we're happy with yet.
Any solution we came up with would have to handle the years and years of feedback in our existing database. Ideally, it wouldn't require big changes to the way the Support Ninjas help people and record the feedback they receive. It would need to prevent folks from signing up for a bunch of forum accounts in order to game the system.
Thus far, when we've discussed it, it's always ended up looking like it would require more engineering time than we're comfortable pulling away from our other projects.
I'm definitely keeping an eye out for good solutions, though - I find some of the things that
uservoice.com has done pretty interesting, for example.