Multi-platform Map Application

Question

I'm working on a web project (PHP, jQuery) which currently using Google Maps powering up the map functionality of the application, however we need to make it multi-platform like you can go to the dashboard and choose one from 5-10 map providers (which Goolge Maps is just one of them) to underlying your map functionality.

So, as the application is supposed to show the data on map, almost in every single place we have to deal with the API provided by that specific map provider. Currently we are thinking about revising our modular structure and/or making something like an adapter for each provider to deal with their native syntax but via our standard methods.

I wish to have your ideas and your experiences, specially if you ever made an interface for dealing via 2-3 different map providers. That would helps much and I really appreciate that.

If you need any further information, just ask me to update the question.

Update:

As Vicky Chijwani suggested Mapstraction, now I'm also wondering which one is more better (pros & cons), having an adapter implemented on Javascript or PHP?