If people really want to use generic reverse names and have realised that the v6 address space is much too big for $GENERATE, one approach is to delegate the appropriate zones to a custom nameserver that can auto-generate PTRs on demand. There are scaling problems here, but probably nothing that can't be fixed with high TTLs and multiple nameservers.
In my discussions with people at some big ISPs, I got the impression that they could do that, but it wouldn't provide any more useful information than no rDNS at all, so they don't. I'm on T-W cable, and there's no way for me to set rDNS. It'd be more trouble than it's worth, since my /64 changes every time the modem reboots which seems to be about once a month. Real servers on static addresses are different, of course. My servers are on an HE tunnel, and all have matching forward and reverse DNS. R's, John