You'll remember I'm using the RSS Reader Panel extension to Firefox as my RSS Aggregator. And it works really well.
Except on this Blog. If you add Linux & Things to your RSS bookmarks, and then click on the link, everything looks normal. On the sidebar below the bookmarks you see the article titles. In the "content area" you see the first few lines of each article. However, when you click on an article you get the message
We're sorry but the Username/Password combination you've entered is either invalid or you don't have permission to access this Blog.
I contacted Blogger support, who gave me a nice answer which showed me that they'd really looked at the problem but, unfortunately, their answer comes down to "not our problem, man". :-( It seems that when Blogger produces its Atom-formatted XML file it produces two links per article. The first is an internal link for Blog*splot, and the second is the permanent link to the article. As far as I can tell, Blog*splot is the only site that does this. I've examined some other Atom files, and none of them seem to have more than one link per article. However, Blog*splot does produce proper XML code, according to http://feedvalidator.org, so I guess it's legal. The permalink is identified as type text/html, while the other link is type application/x.atom+xml, so it shouldn't be too hard to figure out the correct link.
I've posted a bug report with Reader Panel Support, so hopefully this will get fixed soon.