Thanks to a few pointers from Rex Hammock and Charlie Wood I now see that Feedburner is working with Feedblitz to offer RSS to Email functionality.  I just added it to my blog, but in my first few tests the Feedblitz site showed me a "Bad Request" error.  Also, the signup process feels a little clunky.

Hmm, not quite ready or primetime, but it's the right kind of solution (in concept) for a key problem in RSS adoption for the wider population.