There are several benefits to this being part of the blog website itself, not to detract from WGO.
My biggest reason for wanting this is that when I go to Scobleizer’s blog, for instance, I would only see the posts that I haven’t read yet. That’d be cool. I could still view his homepage/blog site from within my choice of aggregator such as NewsGator Online. But, now it would have his theme, his environment.
Why bother? Well, for me I feel like I get more from the blogs I read when they are surrounded by the author’s design choices, including font, colors, images, style, etc. I think the real difference is this: instead of having the news read to me by a monotonous reporter, the person making the news gives it to me directly in all of their flare. When I read blogs in a plain’ol viewer like Outlook (including 2007) and other plain-vanilla readers each blog is presented in black and white, same for each, with less expression. When viewed on the author’s site it is presented in full color in the way the author wants you to see it.
This could be as simple as setting a cookie on my browser to show only newer items or as detailed as creating a free user account with the blog site. A way to re-use your existing account(s) on blogger and the like would be very nice.