When I publish any new blog post, it gets instantly pinged, indexed and updated in Google Reader. How does this magic happen? Its a secret setting in Feedburner.
Until recently it would take from a few minutes to an hour for our latest article to get indexed by all RSS readers like Google Reader. This is because these readers periodically check feed updates. Now it happens instantly!
As you are aware, we use a default Feedburner feed to route our WordPress RSS feed. Feedburner is a Google service and has a setting called Pingshot, which notifies RSS readers of new blog updates. Activate Pingshot and your articles will also start getting instantly updated like us. (Note we use an edited WordPress ping list to directly ping Feedburner).
Go to Feedburner dashboard > Publicize > Pingshot
Post your article, and check if it hits your Google reader instantly. Its happening for us at least.