Feedburner - bought by Google a while ago - is asking every account holder to move all the feeds to a Google Account. The switch is easy, a few clicks on a few buttons to an existing Google Account or you can create a new Google account for this.
On the Feedburner-Google account you can only check feed statistics and no longer site statistcis (Feedburner thinks Google Analytics has the same features - it doesn't IMHO).
My feeds were switched this morning and I'm experiencing loads of "new" old blog-alerts in various AWeber lists that have a connection with Feedburner. Fortunately all my blog-alerts are not on 'Send Automatic' otherwise all my blog readers would have had an avalanche of old alerts!
If you have both a feedburner account and are using AWeber for blog-alerts you better edit the 'blog-broadcast' settings to none automatic sending before you switch Feedburner to Google.