If you have subscribed to blogs on Kindle, and you can download books just fine but blogs never seem to update (and yet you have visited the blog's actual URL and know that it has been updated) you need to restart your Kindle, using the steps below:
Step-by-Step: Kindle System Restart
--Make sure your Kindle is well charged and on (and Wireless turned on (usually, you want your Wireless turned off to save the battery).
--Disconnect the Kindle from the USB or Power Adapter cable.
--Press the Home button on the right edge of the Kindle.
--From the Home screen, press the Menu button on the right edge of the Kindle.
--Select "Settings" from the Home Menu.
--From the Settings page, press the Menu button again.
--Select "Restart" from the Setting Menu.
--Wait a couple of minutes for your Kindle to Restart, then give your Kindle another few minutes to update files, blog posts, etc.
This solution is recommended on the Kindle Daily Nation , and it worked for me, because I was having this problem.
Of course my happiness now may be tempered tomorrow, if the blog doesn't update automatically. Most people don't have to do this...if some people have to restart their Kindle every time they want to update their blog subscriptions, I should think they'd get pretty annoyed - I would.
So hopefully this was a one time thing.