From the ArchLinux Wiki, if you’re trying to update the Album art from Amazon, you’re going to run into a problem:
On May 18th, 2007 Amazon has updated their ECS API. This update has cause the inability of Exaile < = 0.2.9 to retrieve album art. A patch which restores the ability to restore album art retrieval from Amazon has been provided on Exaile's website along with instructions on how to apply the patch. This issue has already been addressed in Exaile's SVN.
The Exaile.org developers have this to say about it:
Amazon ECS 4.0 Update 07.05.16, 03:03 PM
Amazon has updated their ECS API to 4.0 today, which caused Exaile < = 0.2.9 to stop fetching album art. This is fixed in Exaile’s SVN, and there is also a patch available for Exaile 0.2.9 that you can find here. More information (applying the patch, etc) can be found here.