Had some problems when I installed the Feeds Locations plugin in my wordpress blog today. Installation was fine but when I tried to activate the plugin I got "Plugin has invalid header" error. My other blog have the same plugin and it works fine, both blogs is version 3.0.1. The plugin didn't show up in the plugin editor either but I got it running with a quick fix.
- FTP in to you site and goto /wp-content/plugins/wp-feedlocations/
- Download the zip-file with the plugin and extract it.
- Upload the .php file.
- Edit the readme.txt, change the row "Tested up to:" to your current version.
Now the plugin shows up when you refresh your admin page and you can activate it.