From FeedBurner to Google Migration
People migrate from one place to another and now its time for your feeds if you are using feedburner’s services. You need to migrate your feeds to google servers by 28th Feb’09. If you don’t do that, you will no longer be able to access your account at http://www.feedburner.com, and your feeds will either begin returning a “404 Not Found” response or a “301 Moved” response back to your source feed.
The official announcement can be viewed here: https://www.google.com/support/feedburner/bin/answer.py?answer=126303#q11
One of the major change is that you need to have a valid google account to migrate your feeds to Google.