EDIT (May 21): This has been fixed with version 0.91 of the plugin.
Previous answer...
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 */
.olLayerGooglePoweredBy.olLayerGoogleV3.gmnoprint {
visibility:hidden;
}
Restart QGIS to see change. Until OpenLayers's javascript is updated and the plugin author can subsequently upgrade the plugin, it may remain broken. The HTML files for the map renderings already note a Google Maps API of 3.3, so it's not an issue of a missing API version.
This has been reported as an issue in the plugin's tracker. I will reference this page in the tracker.