Along with the recent changes that made media_types into plugins, we moved the media_type config options from config_spec.ini to each media_type plugin. This means that you need to move your 'media_type:' config settings to the plugin section.
from..
[media_type:mediagoblin.media_types.image]
resize_filter = ANTIALIAS
to..
[plugins]
[[mediagoblin.media_types.image]]
resize_filter = ANTIALIAS
If you have are currently using 0.4.1, we have a scriptÂ
http://mediagoblin.org/download/0.5.0_config_converter.py that will make all of the changes to you mediagoblin_local.ini that 0.5.0 requires. Note that currently there is a bug, where if you have "skip_transcode" in your config file, the script will write out [[skip_transcode]], when it should be [[[skip_transcode]]]. Hopefully we will fix this before the release.
Thanks
RJ