I've blogged about this here: http://www.online-archaeology.co.uk/wordpress/ where you can find more instructions on how to load the data.

I think this service-based approach of loading data from separate data sources onto Google Maps provides an exciting future for archaeology. There's a lot more to come as well. We've discussed some other ideas and I hope we can publish these soon.

Nabonidus have also opened up a search web service to allow remote searching of their database. You can use the search function on Online Archaeology here: http://www.online-archaeology.co.uk/Home/SearchNabonidus/tabid/112/Default.aspx