The second beta version of Geeklog 1.6.0 is now available for download.
This release fixes quite a few rough edges in beta 1, for example in the search and the new XMLSitemap plugin. There are a few more issues remaining to be addressed and if you find anything else, please submit a bugreport.
Addendum: If you are trying to install beta 2 over beta 1, you may run into a few issues with the XMLSitemap plugin. Try uninstalling, then re-installing the plugin, as there were a few changes in its config.