A recent article in p2pnet news
talks about an extension to the opentracker codebase that allows trackers to share peer lists via UDP, creating a redundant network. While I wrote the multitracker specification five years ago, I never did develop an efficient data-sharing arrangement for trackers, and I'm glad someone finally has done so.
I am concerned, however, that people are fooling themselves into thinking this is going to prevent legal attacks from shutting down pirate torrents. Instead, it will result in giving the Intellectual Property crowd multiple points of attack in which to either file criminal complaints or sue tracker owners into oblivion. There are a lot of lawyers in the world and there's no reason why the **AA can't go after multiple defendants simultaneously.
I'll say it again: BitTorrent was not designed to evade law enforcement, and if you want to download pirated content you should use a different protocol.
Multitracker BitTorrent is a great thing, allowing even more people to download their content simultaneously, and removing the single failure point for torrents. Just don't delude yourself that it'll keep you safe from the law.