Great comment from Phillip Smith on dynamic OPML:  

If you could succeed in reviving OPML as the de facto "follow a list" standard, that would indeed be a great step toward bootstrapping a more distributed system of feed reading. 

The only thing I'm unclear on is the "dynamic subscriptions." To date, I've not experienced a feed reader that would let me "subscribe" to an OPML source (as much as that makes sense). IIRC, even Google Reader requires one to upload an OPML file, not subscribe to it. 

So, I guess the question I have is: Why isn't subscribing to OPML feeds supported in many RSS readers? 

My response: 

I have my own theories about this, but I want to encourage discussion.  

I would add this as item #4 in my recent list of requests for Twitter client apps. Might as well let the user subscribe to OPML as well as RSS.