There's another alternative that I hadn't thought of, though. A model where the podcatching is done on a computer and then streamed to the portable device. Strictly speaking, this isn't mobilecatching because the "catch" is done on the computer.
I ran across a service called GlooNet which looks like a possible solution. In a nutshell, there's a Windows or Mac application that monitors user-specified folders. Presumably, a podcatcher can be set up to save its audio into the same folders that GlooNet is monitoring. The GlooNet application creates web pages for each directory and provides them to the world using its own internal web server. Assuming you have a web browser on your smartphone and you can download files through it, it seems to me that this can be used as a portable podcasting solution. Or even better, there's no reason why you have to set it up just for you - you could put your own podcasts into the GlooNet directories and offer them to the world. Portably.
The bandwidth problem (in Canada, anyhow) still exists, however.