with this tool you can convert wsprsspots.csv file to the Google kml format. Syntax is convert_win_tx.exe wsprspotsfile yourcall. E.g.:
convert_win_tx.exe wsprspots-2010-01.csv DO1TP
As result of convert you get a kml file that you can open with Google Earth.
Download wsprspots2kml convert here.
Note:
*** One problem is that there are doubled (or more) entries in kml file. I'll fix it as soon as possilbe.
*** convert_win_tx.exe for send amateurs only (SWL version coming in a few days ;)
*** LX version coming soon.