Okay now that was ridiculously easy.... about 30 mins of work while doing my expenses (in other words the 30 mins that kept me sane through the process) and I'd turned the Maps piece into a mapplet piece, which is nice. For those that don't know the "Mapplet" piece is one of the two big releases from Google this week, the other being the truly amazing "Street View".
Anyway a quick bit of hacking around and thanks to having the backend reasonably well done up popped the mapplet
All this takes is a simple Carbon Counter Mapplet XML file. Feel free to give it a go.