Looking at the amount of data our servers spits out to deliver our Chaosradio podcast (sorry people, german only) and seeing that iTunes makes up for a huge percentage of the dopwnloading clients, it’s becoming clear that pure HTTP doesn’t really scale well.
Apple should really, really think about supporting the BitTorrent protocol in iTunes to subscribe to podcasts. The way BitTorrent works makes it the ideal protocol for podcasting as it performs best if many people want to download the same file at the same time which is exactly what happens in podcasting. Many podcasting clients have already endorsed BitTorrent and quite a few video podcasts offer BT as an option.
Apple isn’t known for adopting protocols and file formats not sanctioned by a standards organisation of any form and I doubt BitTorrent is going go through one of these entities in any way. But looking at the latest release of iTunes, Apple has also endorsed OPML which is another (lesser known) very important format of the Blogosphere. OPML is of course much simpler and you can’t really compare file formats and protocols easily. However, I have high hopes Apple might „get“ this as well. I guess before they roll out BT suport in iTunes they should consider buying BitTorrent stock before ;)