• Restructuring of the design process
• User-definable dictionaries to present maps in any language
• Support for spreadsheet data in either tab-delimited format or from Google Spreadsheets
• Support for GeoRSS feeds using the Google Feeds API
• Marker clustering to display large numbers of markers on a map
• Google Street View
• Microsoft Virtual Earth
I’ve played with a bit, and it is easier to use than Version 2 (which is still available). Especially nice is the Google Spreadsheet feature; while Google had a “wizard” that walked you through one way of doing this before, the MapChannels method is far easier to use, and the ability to add GeoRSS feeds and other data makes it more powerful.