Recently, Blogger began appending a tracking gif to the content of each entry in their Atom feeds. The URL used in the image src uses https, most likely to avoid warnings when it’s rendered in a https context. For some reason, when rendering the feed content containing the tracking image, the Flash player can crash, taking the browser with it on certain platform/browser combinations. We found the problem in FireFox 3.0 on OSX, but only on PPC Macs. Go figure.
In our case, we are proxying the Atom feed through a PHP script so we can display the feed contents to user agents without the Flash player. This made it fairly easy to iterate through the entries, and with a simple bit of regex, strip out the offending markup from the contents.
Blogger is wrapping the image tag in a div with a very specific CSS class, which makes our job easy:
foreach($feed->entries as $currEntry)
$currEntry->content = ereg_replace('<div class=\"blogger-post-footer\">.*</div>', '', $currEntry->content);
Depending on what you’re using to parse the feed, you may or may not need to be concerned about decoding and encoding html entities during this process.