PirateBay has moved on from the tracker game, and is now sporting a new logo, and new tech. DHT, or distributed hash tables, will replace the way in which PirateBay interects with torrent files. This really doesn't change anything on your end - you'll still click a link, but now a magnet link, which will open up in your BitTorrent client and download as usual.
From the PirateBay Blog:
“Now that the decentralized system for finding peers is so well developed, TPB has decided that there is no need to run a tracker anymore, so it will remain down! It’s the end of an era, but the era is no longer up2date. We have put a server in a museum already, and now the tracking can be put there as well.”
I'm sure there's a lot more to it then that, but it's really over my head the technical aspects of this change. What I do know is that DHT used to be utilized by direct peer to peer applications, like Napster and Gnutella. From what I've read and understand of this development, PirateBay is doing this to get out of some loophole legal stuff - since they want to be likened to Google, in terms of being just a search engine of torrent files. By not going through a tracker, and instead going forward with DHT, they no longer are tied to the host file itself, although this is a bit debatable.
[PirateBay Blog via TorrentFreak]