GPS2Aperture Lite is a free and simple geotagging application for use with Apple's Aperture and Google Earth. You can view GPS positions of images in Google Earth, and embed GPS positions in the Master file for a Version.

GPS2Aperture does make changes to your Master files to embed the GPS data, but it does so using EXIFTool, the same command line application that is the basis of HoudahGeo and several other popular geotagging programs.

The current beta version can be downloaded here.

Note that 'Make KMZ' isn't working yet, and the next and previous buttons aren't working reliably in floating mode.

Future plans for GPS2Aperture are to keep this version completely free, and have a paid version which will geotag from GPS log files with the same visual help from Google Earth. The paid version will be part of Aperture Assistant, but will also be available separately for a lower price.