EDIT (May 21): This has been fixed with version 0.91 of the plugin.
This has been discussed recently here: http://gis.stackexchange.com/a/20608/6725
As per the suggestion there, you can edit the Open Layers plugin to hide the white box.
Edit [path to your user plugins]\openlayers\html\google.css
- Linux and other unices: /home/$USERNAME/.qgis/python/plugins/
- Mac OS X: /Users/$USERNAME/.qgis/python/plugins/
- Windows: C:\Documents and Settings\$USERNAME.qgis\python\plugins\
/* Add this to end of file */
This has been reported as an issue in the plugin's tracker. I will reference this page in the tracker.