Don Park posted a few improvement requests for Radio, including: 

• Category post to e-mail
• Private Category to Public Categories - while most news aggregation is happening at the client end, there is room for intermediate news aggregation that aggregates posts from multiple blogs. User can set this up by specifying one or more post destinations, each corresponding to a Public Category.  This feature leads naturally to introduction of editorialized news and invited columnists.
• Syndicated News Filters/Prioritizer - I subscribe a good set of RSS feeds, but I am usually interested only in certain topics.  It would be nice to be able to filter or sort news by requiring presence or absence of certain words and phrases for each subscribed RSS feed.  Also, it would be great if I received regular reports of words and phrases my RSS feed subscribers are interested in.

His first one--category post to e-mail--sounds like something that could be done, in reverse, using Radio's mail-to-webblog feature.  I haven't played with this feature, so I'm not sure what the effect would be (would it reflect the address of the listserve or other recipients?  can you specify categories or a title when you post this way?).  I have thought about trying to automate this for myself in Outlook, though--there have been a few posts I've made to listserves that I've wanted to have here, too, and rather than cut-and-paste, I've thought about setting up a macro for myself that would allow me to send the message to the listserve, automatically reformat so it Radio could read it, and then send it to my Radio e-mail address.  Maybe this will be a project for the weekend.

As for Public Categories and a syndicated news filter/prioritizer--I talked about both of these sorts of things before, here (the HPANA--Harry Potter Automatic News Aggregator is essentially a feed from multiple feeds, specifically relating to Harry Potter news) and here (which is where I started thinking about this).  My thoughts were prompted by this post on Scripting News linking to this site, which is a group of people thinking about these things.

So, I post it here, simply for my own future reference.