FTP has long been a mainstay of transferring files, but it’s been plagued by problems due to its centralized nature, especially for popular files: if the site is down you can’t get it, central or popular sites are often slow, mirrors get out of sync, etc… File sharing a la KaZaA/Gnutella is an alternative, but then you have to search for what you want and hope it turns up, connections aren’t reliable, what you get might have a virus…
Fortunately, these concepts have been merged into newer programs like BitTorrent and eDonkey, where you download chunks of the file from other people who are also downloading it. The bandwidth requirements are thus scattered across a large number of systems, you don’t depend on a single site, and the result is checked against the original package description to ensure integrity.
As an example, the Slackware 9.1 ISO images were released last week, but it was almost impossible to get on the main site or any mirrors and download it at a decent rate. Using the BitTorrent links instead though, I was able to immediately download both ISOs at over 250kB/s. At the same time, my client exported about half of the ISO data, which in turn helped other people who were downloading the files.
They’re certainly not a complete replacement for FTP yet, but hopefully we’ll see the usage of these kinds of programs on the increase. A lot of large data files like movie trailers, game demos, etc. can certainly benefit from this kind of distribution. Otherwise you’re stuck with services like FilePlanet where you wait forever in ‘line’ to download a file at a way too slow rate…