In the past, Pamela's blogged about ways to create map mashups out of published spreadsheets using the Spreadsheets GData API. Well now we have a more integrated approach using spreadsheets gadgets. For the uninitiated, here's a spreadsheet gadget I'm using to plan my road trip:
It's reading data from a simple spreadsheet and displaying it here. Any changes a collaborator makes to the underlying spreadsheet will be reflected on this page. So what's new about this approach? Spreadsheet gadgets can be embedded directly in spreadsheets, like the heat map in this sheet, or even on on their own sheet. And spreadsheet gadgets can be accessed from within Google Docs Spreadsheet's built-in gadget picker, so they're very easy for everyday folk to discover and use.
For more info, check out our post on the Google Gadgets API blog.