Google provides this bulk upload for to allow businesses to easily add their listing to Google Maps. If you have multiple locations, this is the easier way to do so. Yes, this solution has been taken advantage of and Google has been working up solutions to prevent local and map spam from happening too often. But yet, there are concerns of business listing hijackings and other concerns.
In any case, Google Maps Guide Jen, replied to the thread saying it has now been resolved.
This issue should be resolved! Thank you for bringing our attention to it so promptly.
So if you missed this feature, it is now back in action.
Forum discussion at Google Groups.
Update 1/8/08: This is still not working, an update comes from Google Groups where Maps Guide Jen confirms they are still working on a fix.
Sorry, as you've all noted, it's still broken. Work continues... Thanks for continuing to be patient.