Google Base says "This website URL is already in use..."

When setting up your Google Base account, you must specify the store URL under the settings tab. If you specify a URL that has already been registered at some point in time with Google Base, you will see a message, "This website URL is already in use by another Google Base account". To correct this, simply fill out this form:

http://base.google.com/support/bin/request.py?contact_type=howto

Google will let you know when they have reset your account. Or you may check your account in a couple days and try entering your store URL again. For more info, visit their help article here:

http://base.google.com/support/bin/answer.py?answer=25191