While at Torcamp I have heard from several sources that Rogers and Shaw are blocking podcast downloads. After two to three downloads, the data stops.
I highly doubt this is true: I subscribe to several podcasts here in Vancouver, and am connected to Shaw. No blockage here. If this *is* true, it would be a major issue (kind of like throttling BitTorrent traffic). Alec, let's get confirmation on this, because it doesn't sound realistic right now.
Update: Patrick Dinnen left a comment, pointing especially to Apple forums where this is being discussed. Virtually all of the complaints seem to be limited to Rogers customers back east. The factor seems to be anything that downloads the same file from multiple servers -- which is consistent with Apple's use of Akamai, as well as P2P programs that use multiple download sources.
Other links: digg pointing to this Techdirt article, also pointing to Boing Boing bringing it up. Still no confirmation, but it wouldn't surprise me if it's Shaw/Rogers not blocking podcasting, but rather having misconfigured traffic shaping tools.