I spent my evening developing this extension for ExtJS 4.
What's Ext.ux.GMapManager? Just a singleton that manages multiple google maps with multiple markers.
Is it a google maps wrapper? No, it isn't! And yes, you still have to use google maps API. However, Ext.ux.GMapManager helps you in many ways
Here's a screenshot:
And here's a live demo: http://www.wilky.it/public/Ext.ux.GMapManager/
While here's the documentation (made with JS Duck): http://www.wilky.it/public/Ext.ux.GMapManager/docs/#!/api/Ext.ux.GMapManager
I hope you'll enjoy it