I installed and played a bit with the mashup package and found it very impressive.
I'm not sure if it is a problem in my installation, but I discovered that the only way to make the portlets draggable is to disable the developer-support package. Hope that this can avoid to other people a debugging session.
Another question is that I got a Google map key and set it into the corresponding parameter, but nothing appears on the page and I have no clue as how to proceed.
Many thanks to you and Solution Grove for your valuable contributions!