In the meantime ReadWriteWeb has an interesting post on a new feedreader, called fav.or.it that:
...lets you read feed content and comment, all within the app. The comments can be two-way, meaning publishers can choose to aggregate fav.or.it comments into their blogs.A video also gives you an idea what it looks like and how it works.
Is this the answer to my question? It sure looks like it! But we'll have to see in practice. Soon they'll be open to the public.