Recently (not long after WP 3.4 upgrade) a batch of our subscribed feeds are failing with:
The data could not be converted to UTF-8. You MUST have either the iconv or mbstring extension installed. Upgrading to PHP 5.x (which includes iconv) is highly recommended.
Our server is running PHP 5.3.10 and iconv is enabled.
These feeds are coming from another wordpress site (we are resynidcating based on a tag at the mother site)