I wrote a post a couple of days ago describing problems that some readers of this blog who use Google Reader and Bloglines were having if they had subscribed prior to January. Unfortunately, the problem appears to have worsened, so I would strongly encourage you to re-subscribe using the newer Feedburner feed. This issue only relates to people who have subscribed prior to January — anyone who has subscribed since then is already using the Feedburner feed and shouldn’t be having any problems.
Other RSS Readers don’t appear to be having any issues, so I think this only relates to “older” Google and Bloglines subscribers.
Sorry for the inconvenience, but the problem appears to be out of my control.