What I think is a better idea was proposed here last year, and I think someone was doing it for a while. It is for someone to volunteer to be the keeper of the remailer aliveness information. He runs scripts every day to ping the remailers, keeps lists of which remailers are currently active, and so on.
This does seem like a better idea, except for one thing: Everybody has got to trust the Keeper of the Aliveness Info. I'm not sure how much of a problem this is, nor am I sure that the newsgroup method neccesitates any less trust.
A major problem with having a single-point aliveness-info source is that watching traffic to that source gives you some idea who's about to send anonymous messages - multiple sources mean there are N sources to wiretap to get the same information, which may be nearly as bad. On the other hand, a broadcast method like a usenet group has the advantage that you can read the newsgroup without being very obvious, except locally. A mailing list is somewhere in between. Similar problems occur with anonymous single remailers in the absence of good reordering; many new remailer users, or users of unreliable remailers precede their real anonymous messages with a ping of some sort, such as a message through the remailer chain pointing back to themselves. If you're using a news reader without NNTP, or with NNTP only for the local non-tapped LAN, you may be ok. Another alternative are mailing lists (NOT human-readable ones like cypherpunks) which reforward the remailer newsgroup information, preferably encrypted. Newsgroups are obviously easy to inject bogus information into, but that's the way it goes; any non-trusted system is, well, non-trusted.... Bill