I've just done a demonstration page for a tourism group who are currently using Google maps to pinpoint locations of accommodation providers.
You can see it here:
http://www.visittweedvalley.co.uk/osmapdemo.html
I think Google might lose out here, there's more detail, and it's much easier to add content to the pop-up information windows on the markers (it's possible in the Google map module used in the Drupal content management system, but it's all hand-coded).
