Let two great plugins play great together. Use FeedWordPress to aggregate geodata generated by GeoMashup.
You must have FeedWordPress and GeoMashup installed, activated, and configured in order for Feed GeoMashup to do anything. Please see the independent documentation for those plugins.
VERY IMPORTANT: You must additionally configure FeedWordPress to "Expose syndicated posts to formatting filters." Do this on the admin side at: Syndication > Posts & Links > Formatting > Formatting filters.
Once you have those pieces in place, you can activate the plugin and start pulling in GeoMashup maps.
Go to "Syndication > Posts & Links" in the FeedWordPress admin interface to set filtering preferences.