There is a rather big problem for those that use the direct link to the feed-generating files in WordPress (i.e. wp-rss2.php, wp-rss.php, wp-rdf.php, wp-atom.php and wp-commentsrss2.php) on blogs that upgraded to WP2.5/2.5.1, either in their own feed readers or (in my case) as the feed FeedBurner reads. They don’t send anything out in many cases.
I found that out the hard way when my last 2 posts did not get sent out to the feed, and some comments made after the upgrade also didn’t make it out. Fortunately for you guys, the fix needed was entirely on my end as I switched FeedBurner to read the more-nebulous …/feed and …/comments/feed URLs (since I have Pretty Permalinks set up), and I have the FeedBurner FeedSmith plugin directing all of you to FeedBurner.
Unfortunately, those blogs I had my feed reader set to go to wp-rss2.php will have to be reset to read either the …/feed or …/?feed=rss2 URL, depending on whether they have Pretty Permalinks set up or not. That’s going to be a major pain in the ass.
Revisions/extensions (10:25 am 4/29/2008) – It is specific to WP 2.5.1. I haven’t seen any real mention of this in the WordPress forums, but as Peter has told me, the upgrade sure feels like going from Windows XP to Windows Vista.
R&E part 2 (10:34 am 5/3/2008) – Bringing up word of a patch from the comments. Thanks Nicolas.
There is a fix available at trac.wordpress.com ; that should avoid your users migrating from wp-rss2.php to /feed/
Hope it helps,